|"around 400W+" means even less. That card is gonna use about 10 amps of +12v power (120 watts) and a power supply of "around 400W+" probably just ain't gonna cut the mustard. That's a big power draw for even a "good" psu.|
"Would be able to run most games as bioshock, fallout 3, oblivion, basicly just all games in highest graphics or atleast medium?"
We just can't answer that. We do not know what processor, what memory and how much memory, what motherboard or power supply specs.
You think we want to say the 9800GT is a dandy card for you and then wait until you post back saying the system won't boot or the power supply went "pop!"?
You're looking at spending £105 just for the card and £150 or so for a card and quality power supply. You need to answer our questions...£150 will go a long way for a decently modern system but can also be money thrown in the trash for an outdated weak system.