Re: Entertainment and Gaming Powerhouse
Well, if you are on more of a budget, what you have is fine. Although I would get the Vista 64-bit Home Premium OEM version. It is all that you would need and is only $95 or less.
Right now, Intel has the quad core market wrapped up. Get a Q6600 OEM for only $199 which will outperform ANY of the AMD quad cores. For a media PC you may want more HDD space. If that is the case, grab 2 or as many as you need of the Seagate 500GB 7200.11 HDD's.
You really don't need that powerful of a video card to still get full HD movies and max settings on games. But a good 1GB card would be the 9800GX2. Otherwise you would be more than set with an 8800GTS 512MB and have room to upgrade when the newer (hopefully far better) cards come out.
It sounds like you are investing quite a bit of money into this, and right now to get the most out of what you spend, you will need an Intel system.