There are a few things to consider:
1. Gameplay
Well I think it's the lames thing to play any kind of 1st/3rd person shooter/tactics/rpg via gamepad. There was a trial phase where PC users could access to XBOX live but this has been cancelled after Microsoft must have realized that console gamers didn't have much of a chance to stand against PC gamers in certain genres.
Of course a gamepad can be useful. I own a Xbox 360 gamepad for my PC as well, but I use it only for racing games.
2. Graphics/Performance
Xbox360 and PS3 are both outdated hardware and can't handle top notch graphics game very well. The developers have to reduce the resolution below HD, disable features like anti aliasing and screw around with other tricks to make graphic intense games running more or less playable.
3. Game Experience
Consoles are probably the better choice if you like to play some stuff via splitscreen with some friends in your living room. At least I'd say it's a bit nerdy to gather your folks in front of a PC^^
Conclusion:
If you already have a half-way decent computer (fast dual core or quad core, >4GB Ram) you can upgrade it with a new graphics card. I think the costs would be something around 200€ to make any game run with very high graphics settings. I bought a "MSI GTX 560 TI" as "like new" condition with 12 Month warranty for 141€ bucks a week ago and retired my old 8800GT I've bought in 2008. Having a fast graphics card installed gives you also some other advantages since many programs including GPU acceleration (e.g. for video rendering).
If I had to choose a console I'd go with the Xbox. Not that I'm a M$ lover but it turned out that the 256MB Ram is a very bad bottleneck for the PS3 compared to 512MB Ram in the Xbox. Of course both values seems ridiculous in 2011
@Fallout 3/New Vegas:
I like both games but I think the main story was better @Fallout 3. Still you get many, many hours gameplay for the price.
PS: Do we have anyone from US using Steam?
I'm looking for somebody to gift me a game every now and then (of course I pay in advance). Some games aren't available in germany, other are somewhot "violence reduced" and last but not least steam seems to think that "1EURO = 1USD" so I have to pay effectively more
