$1,500 will buy close to the best gaming system available right now. Hell, even with one of the latest gen video cards that are $500 you could still do it easy. The following recommendation is for a massive budget, not necessarily what I would recommend to most people:
<UL>
<LI>Intel Pentium 4 2.4 GHz C-core at 800 MHz FSB
<LI>ABIT IC7-G, Intel 875P chipset for Socket 478 800MHz Canterwood ATX Motherboard
<LI>CORSAIR 512MB PC3200
<LI>Sapphire Radeon 9800 Pro
<LI>52x24x52 CD-Burner
<LI>Floppy
<LI>80 GB Maxtor 7200 RPM
<LI>Thermaltake Volcano CPU Fan
<LI>Generic Case
</UL>
That PC will put you right at $1,100 not counting shipping. Of course, if you switched to AMD and went with an Athlon XP 2500+ and a Abit NF7-S you would save a ton of money and not lose too much performance. Either way, both of the CPU's listed are VERY overclockable. And if you're not into OC'ing, then they are both great CPU's at regular speeds. You could also switch out the Radeon with a GeForce FX 5900 Ultra if NVIDIA is your thing.
This is all going on the fact that you know how to put together a PC, or know someone who knows how to. If you don't, then I have to suggest Dell.
Your gaming won't be nearly as good (quite frankly, it will probably suck), but at least it will come built.
My point is that you can get one hell of a PC for under $1,500.00. Good luck with your purchases!
-Lasereth