Why go through the middleman, who robs you of your bucks? My current computer, built in 2002, consists of a 2.54 GHz processor with 2 GB RAM, a 30 GB C: drive a 120 GB D: drive, 200 GB of offline/backup storage and a 4X video card.
Cost? $700. And it's still serving me extremely well, today. I BAUT (there's a new verb for you), watch movies, do research...
The only caveat I would have is that you give yourself a bit more room on the front end, as I only have 5 GB left on my C: drive, with no files (personal folders) on it. It's all prgrams.
So, please give yourself enough room up front.
Other than that, build your own. Have at it. Have fun! You'll learn something.
Here's an excellent link.
That's the site that I've used since 1994 and three home-made computer upgrades. The just get things right!
But if you want to pay the man the addition $700 to $1,500 for the exact same thing, that's your choice.