Well, from personal experience do NOT use Dell. They have TERRIBLE customer service. They sent me a defective computer and I had to PAY to ship it back. So don't use them!
Also, do not order a computer through the mail using any other company either. During shipment, the fans come lose and cause loads of problems! Mail delivery with computers is bad!
From experience, I wouldn't use Best Buy ever again either because they have TERRIBLE customer service as well. It wasn't until I got completely ticked off and sent them an angry email that they actually suggested something helpful. They kept trying to blame my computer problems on ME. It was not me. The computer was defective when I bought it! So yeah, if you use Best Buy and have problems, you may have even more problems with customer service. Just be stern with them!
As far as brands are concerned, never EVER buy an E-Machine. This is what I bought from Best Buy and it is a POS. I'm serious. I have had so many problems with this computer. E-Machine is a subsidiary (sp?) company of Gateway. I wouldn't buy a Gateway for that reason either.
Now, my brother and sister have HP's. My brother in fact has an HP laptop and desktop. My sister has a newer desktop. They have had ZERO problems out of their computers.
In conclusion, I suggest getting an HP. I think these are good quality computers. Try buying the fastest computer you can afford. Getting a lot of space is nice too.