Humm...this became a long one
Well, then Vista is installed and running smoothly. No issues with the installation at all, except for one device that I don't have drivers for (and have no idea what is

). My comp is, strangely enough, also FASTER than what it was in XP.
So far I've tested Auto Assault, WoW and Red Orchestra on the gaming-side. RO has issues connecting to other LAN-games through Hamachi, quite possibly due to the firewall in Vista (even though it's deactivated for both Private, Local and Public networks). Internet-games are no problem at all, and the game seems to run smoother than before. WoW has slightly higher FPS than when running on XP (5 to 8, even in Darkshore, with all eyecandy turned to max). AA had to be run as Administrator in compatability-mode, but other than that: no problems what so ever.
The only REAL issue I have with Vista, is the fact that Microsoft has done away with pure Directsound and gone over to OpenAL instead. What does this mean? Well, no true Quadrophonic speaker-output from my Realtek Azalia soundchip over two different sets of speakers, for example (running a Logitech Z-210-set as front-speakers, and have a Marantz PM30 amplifier with two Marantz speakers as rear units). I get a strange, flat sound from my rear speakers, and it sounds like the rear speaker-set drives the bass and low tones, while the front does the higher tones. It works, but it's not ideal (especially not in games, even in Red Orchestra, which supports OpenAL).
What remains to be tested? Well, there's always a stack of games (yep, I'm a gamer even at 31, and I'm damn proud of it

). I don't suspect any errors or problems with newer games like HalfLife 2 or Dawn of War:Dark Crusade, but I am curious on how games like IL2 (which uses OpenGL) runs and looks, and not to mention how Lock On:Flaming Cliffs will behave. LO:FC comes bundled with the oft-hated-upon Starforce III (please spare me the comments on how evil SF is, as I've yet to come across a problem with it), so there'll be some poking around on the boards to check before I install it. I know there's a patch from Starforce that needs to be installed, but that's about the limit of my knowledge about it at the moment.
Quick-list of likes:
Windows Mail: (Built-in mailclient). Wonderful piece of software compared to the old Outlook Express-variants. It even has a spamfilter that works straight out of the box, which is more than I can say about Thunderbird (even though that's good as well)
Aero: Yummeh, even IF it is a rip from MacOSX (why not copy it if it works and looks beautiful?). MacOSX still looks better, though, but Aero isn't far behind in my opinion. And it's a far cry from the bubblegum-GUI of XP.
Driver-support: Vista has good support for older units (not TOO old, mind you), but with the change of the sound-system in DX10/Vista, my old Creative Soundblaster Live 5.1 is obsolete and without drivers. But on the plus side: It found my ViMicro Webcam, which is a hideous BITCH in XP, straight away without problems. And now that most hardware-manufacturers has managed to put out drivers, most things work (still wondering what the Communications Device without drivers I have is. Suspect it's either a part of the Marvel Yukon NIC, or possibly something in the Intel ICH8R-chip that's lacking the proper drivers

)
Performance/Stability: Vista, at least on my setup, seems faster than a newly installed XP. No errors, bluescreens or obvious bugs noted, no abnormal resource-usage discovered etc. How this will hold up will be interesting.
Now to the list of the things I DON'T like....
UAC (User Access Control): Annoying as hell, to be honest. True, it's an extra layer of insulation between the user and the core system, but when I want to change something; CHANGE IT! Take your messages and stuff it up your PCI-bushandling-routines, ffs! Luckily it's easy to disable, which was probably the first thing I did after installation.
Triple-layer firewall: While a good piece of software and seemingly good enough to protect the computer from mundane attacks (wouldn't trust it against a determined attacker that knows what he/she/it is doing), but annoying that I had to disable it through the Windows Firewall with Advanced Security-option that hides in the Administrative Tools in the Control Panel (had serious issues in getting a certain piece of software that I run to work

Kept getting these annoying Unable to Connect-messages from the client-part

). True, can always add things to the various exception-lists, but since I run a hardware-based firewall with NAT, I don't need (or want) a software-based firewall active.
Changed Audio-routines in DX10 compared to DX9c: Annoying that I have to fiddle so damn much only to activate two-channel sound. If this is due to OpenAL, the soundcard-drivers for the Azalia-chip or merely a stupid user (namely me) is unknown at this stage.
Quick list of things I'm not sure if I like or not:
Movie-files as desktop backgrounds: A nifty, yet somewhat redundant feature of Vista Ultimate. I don't sit around staring at my desktop all too often, but it IS kind of nifty having Bo Derek climbing out of the surf in a bikini in DVD-quality on my desktop

The novelty wears off quick, though.
Windows Sidebar: Nifty piece of software, but since I'm a bit strange like that, I don't really like things that limits applications from using the full width of my desktop (can probably tweak that so that it's not always on top). Haven't found all that many good Gadgets yet, either (a Gadget that lets me know when it's time to turn to Mekka to pray to Muhammed isn't really something I need

)
The new Start-menu: Haven't warmed completely to it yet, most likely because it's new/changed compared to the one in XP. Will continue to use it and see how it goes from there.
Things to be tested:
Domain-integration with the Windows Home Server Beta, performance in Poser/Bryce/Painter, benchmarking/stresstesting, setting up synchronization between the computer and my cellphone, and Windows ReadyBoost (using an USB memory-stick as RAM).