Pretty much no...
You're looking at at least 700-800 bucks for an entry level system. If you had an optical drive and a hard drive to carry over and you only had to worry about central components, 500 bucks would be doable. But it wouldn't be a hot rig by any stretch...
Basically you need
PCI-E Mobo (Socket 939 or a comparable board from that 'other' company)
1Gb of PC3200 (or greater)
PCI-E Video Card (6600/X600 or greater)
Entry Level Processor (Athlon 64 3000 or comparable)
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Thats gonna ring in around $500, maybe a bit more.
You can price it on Newegg if you want, but I think thats around $500ish. You'd still need
HDD (80Gb, 7200 RPM 8Mb Cache, or greater)
Optical Drive (DVD required)
Case/PSU (400W or greater, make sure it has good ventilation)
120mm/80mm Fans for front and back of case
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$200-$300 (a bit more if you want a stlyish case)