Also, call around your local shops and find out if they will build a custom system.
I just bought a new system last week. I specced it out myself, since I was originally intending to build it myself. Just for grins, I emailed the specs to a local computer shop who will custom build systems.
1 Black Mid Tower Case SN:2005031801
1 450W Power Supply
1 AMD Athlon 64 3200+ SN:1194027B50585
1 Asus S939 Nforce4 PCI-Ex R 1 GE SN: 51ZG041789
2 512 MEG DDR 400 PC3200 Memory SN:1823880, 1823886
1 Western Digital 200 Gig SATA Hard Drive, 8MB, 7200 RPM
SN:WCAL81593971
1 Samsung CD-RW SN:M2946GBY107079
1 Samsung DVD ROM SN:L7976RFX93920 0.00T
1 Nvidia GeForce 6600GT 128 Meg
PCI Express Video Card SN:56368471850
Plus OS, mouse, etc. I already have a monitor. All for $1500. Which was nearly the same as I would have paid with shipping to order the components and assemble it myself.
For less than $100 difference, I get full on-site tech support for one year & free replacement of parts for one year. Also, the company ran into some issues with getting the mobo to fit the original case (which according to the spec, should have worked fine) and had a problem with the DvD/RW that they recieved (bad part, it happens), but I got a DVD player and separate CDRW, plus an upgraded case for free, and I didn't have to deal with the headache of shipping parts back (more postage) and waiting for a new delivery.
All in all, I was pretty happy doing it that way. Although I think I really will build my next system, just for fun!
Cheers,
Spitter