Well then, in that case we can definitely hit you up for some good computer-building fun. I'll start with an Intel solution.
Motherboard:
ASUS P4P800S Retail - $69.00
Processor:
Intel Pentium 4 / 2.4C GHz 800 MHz FSB 512K Cache, Hyperthreading Technology - Retail - $169.00
RAM:
[url=http://www.newegg.com/app/ViewProductDesc.asp?description=20-145-479&depa=0]Corsair Value Select 184 Pin 512MB DDR PC3200 - OEM - $79.00
Graphics Card:
SAPPHIRE ATI RADEON 9600PRO Video Card, 128MB DDR, 128-bit, DVI/TV-Out, 8X AGP -BULK - OEM - $126.00
Storage:
Maxtor 80GB 7200RPM IDE Hard Drive, Model 6Y080L0, OEM Drive only - $70.50
CD-RW:
ASUS Black 52X32X52 IDE Internal CD-RW Drive w/ QuieTrack Technology, Model CRW-5232AS QuieTrack, Retail - $36.00
Case:
RAIDMAX Black Mustang 10-Bay ATX Mid-Tower Case with Front USB 2.0 and 350W Power Supply, Model "ATX-289WBP" - RETAIL - $32.00
Floppy Drive:
NEC 1.44MB Black Internal Floppy Drive, OEM - $10.99
Operating System:
Microsoft Windows XP Professional with Service Pack SP1a - OEM - $141.00
Total: $733.50
However, this estimate makes several assumptions. 1) you're not going to transfer your current HD, or OS. If you are, subtract $211.50, and it brings ya down to 522, right, in the middle of your range.
However, if you're looking to go with an AMD solution, here's one I like:
Mobo:
ABIT "NF7-S" nForce2 Chipset Motherboard for AMD Socket A CPU - RETAIL - $82.00
Processor:
AMD 45 Watt Mobile Athlon XP 2500+, 266 FSB, 512K Cache - OEM - $88.00 I recommend this one over the other 2500+ Bartons because it's not locked.
Graphics Card:
AOpen nVIDIA GeForce FX5900XT Video Card, 128MB DDR, 256-bit, DVI/TV-Out, 8X AGP, Model "FX5900XT-DV128" - RETAIL - $174.50
The RAM, storage, CD-RW and floppy can stay the same.
Total:
$634.99 (HDD & Win XP Pro OEM included.)
$413.49 (no new HDD or WIN XP Pro)