I have long debated this issue with my friends as I am a hardcore PC gamer, and have been for the last 10 years. I recently bought my son a 360 so I have been struggling over whether to upgrade my aging PC. (Dell XPS gen 3)
I think the OP hits some major nerves. For one, I too have grown weary with the constant upgrading. At first it was like a hobby and I enjoyed it, but with increasing cost it has grown tedious, not fun. I also grow weary with every new game coming out needing to be "tweaked" to run well. I had to do this even when my PC was current. You still need to tweak this and that to squeeze out max FPS. Just read the article on Crysis - it is the same with every game. Sometimes ATI drivers are disadvantaged, other times it is Nvidia. Sometimes it's the sound card. With the 360, I know if I buy it and stick it in the drive it will work well and play well. (assuming the 360 works, LOL, with the ROD, etc.)
But, the controllers suck compared to a mouse. I really like the 360 controller's design, but you still lack the precision of a mouse.
The reality is every major game developer's primary development thrust is consoles first, then the PC gets the port. I have read up extensively on this topic and that's the truth - because that is where the money is. Read this:
http://www.gamasutra.com/php-bin/news_index.php?story=15861
COD 4 will outsell Halo because it was released across all console platforms in addition to the PC, and the PC will barely show a dent compared to any platform sales.
With the exception of Crysis, there is no AAA game coming out that will not be released on a console. At E3, every game was being shown on a console, not a PC. The reality is if you don't already have a gaming rig and want to start gaming, you are better off with a console, unless you want to play MMORPG's. Multiplayer on the 360 is also very weak compared to PC's. For example, COD 4 supports 32 players on the PC versus a measley 18 on the 360.
So, really, it is a tough question which way to go - but I am unlikely to upgrade and get a new rig like I have every three years in the past. I just don't see a future in PC gaming anymore. And believe me, if you knew me, for me to say that is a major act of heresy.