[ QUOTE ]
(and for whomever suggested that CoH uses DX9, it doesn't, it uses OpenGL)
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City of heroes does use DX9 
Minimum System Requirements:
Microsoft® Windows® 2000/XP
Intel® Pentium® III 800 Mhz or AMD Athlon 800 Mhz
256 MB RAM
CD-ROM Drive
4 GB Available HDD Space
NVIDIA® GeForce 2 Series, ATI® Radeon® 7500 or Intel® i810G Series Video Card
16-bit Sound Card
56k modem
DirectX® 9.0c
Recommended System Requirements:
Microsoft® Windows® 2000/XP
Intel® Pentium® 4 2.0 GHz or AMD® Athlon XP 2000+
1 GB RAM
16X CD-ROM Drive
4 GB Available HDD Space
NVIDIA® GeForce 6200
16-bit Sound Card
Broadband Internet Connection
DirectX® 9.0c
DirectX is probably used for sound, hence the requirement, but the graphics engine is OpenGL.
@SteelRat; @SteelRat2
"Angelina my love, I'm a genius!"
"Of course you are darling, that's why I married you. Physically, you're rather unattractive"
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Would CoH work better on Vista?
Consciousness: that annoying time between naps.
Your description of what's happening sounds very familiar. I had the same sort of thing happen to me a couple of years back after upgrading the graphics card.
Speaking from my own experiences it sounds like the PSU you have at the moment isn't large enough to run the graphics card.
Forgot to mention, knackered 2 graphics cards before the PSU finally burnt out out as well 
[ QUOTE ]
Would CoH work better on Vista?
[/ QUOTE ]
It can do but there are a different set of graphics driver issues there in regards NVidia.
As it stands it sounds more as if your problems are hardware related and you should resolve those before adding any issues with a change of OS.
I still suspect your problem is in either your graphics card is underpowered or is overheating. Remember most cheap PCs these days come with the cheapest PSU they can get away with. A quality 500W PSU will outperform a budget 800W one. The card must be correctly connected to the PSU - if you don't have a manual for the card you will find one on the card manufacturers website - or their support will be able to tell you how the card should be connected - they do after all have a vested interest in making sure it works correctly but make sure you know the exact model of card including version numbers.
Mind of Gaia lvl 50 Defiant's first Mind/Storm 'troller.
Deadly Doc 50 Dark/Dark Corr
and lots more on Pinnacle,Union and Defiant
np
.. of course it's really only good advice if it works 
@SteelRat; @SteelRat2
"Angelina my love, I'm a genius!"
"Of course you are darling, that's why I married you. Physically, you're rather unattractive"
http://faces.cohtitan.com/profile/SteelRat