I just read the first post.
Honestly, if you are living in America, those prices are no where near acceptable. I always recommend to build your own but that would probobly be way to overwhelming for you. Just get a Dell and find a coupon code and you'll get a good deal.
I just got a new laptop from dell for college, and I got $600 off. My laptop cost about as much as the more expensive of the 2 computers you provided, and it has way better specs. And we are talking about a laptop here... those prices are unnacceptable.
Try to get
1.Core 2 Duo
2. 2GB of RAM
3. A good graphics card. An 8600GT would probobly be pretty good and not too expesnive. Of course you could always get an 8800gtx 
And in regards to the graphics card, if you get a computer from Dell, like I reccomended, or even anywhere else, I suggest that you get the computer without a videocard, (make sure the motherboard has a PCI Express slot though!) and install the videocard yourself. While you may be a complete noob, installing a video card is very very simple, and you save quite a bit putting it in yourself.
Well that's all I have to say. Good luck.
Here's a video from my band's last show Check out more (bigger) videos here http://www.youtube.com/user/icemanout
