Under $1500 eh?
Intel E6850 3.0GHz Dual Core Processor
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115028
Gigabyte GA-P35-DS3L Motherboard
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128059
Crucial Ballistix DDR2 800 2 x 1GB (2GB) RAM
http://www.newegg.com/Product/Product.aspx?Item=N82E16820146565
Seagate Barracuda 7200.11 500GB HDD
http://www.newegg.com/Product/Product.aspx?Item=N82E16822148288
Corsair 450VX 450W Power Supply
http://www.newegg.com/Product/Product.aspx?Item=N82E16817139003&Tpk=Corsair+450VX
Samsung DVD+/-RW Drive x2
http://www.newegg.com/Product/Product.aspx?Item=N82E16827151154
Now the fun part begins: You can choose your video card (If you can get an 8800GT in stock, that would be a great pick up, or a 3850/3870 depending on how much you want to game/how high you game). Here's one:
EVGA 8800GT (make sure to register it on their website for lifetime warranty!)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130303
Also, picking the case you like (both aesthetically pleasing and functional). For a good budget case that works quite well:
Cooler Master Centurion 5
http://www.newegg.com/Product/Product.aspx?Item=N82E16811119068
All that and your price comes out to $1056.91 before tax or shipping. Add in an OEM copy of Vista or Windows XP depending on what you want and you're looking at $1200 before tax (if in CA) or shipping. Probably $1250 shipped w/o tax. And this isn't even looking at deeper deals w/ possible rebates etc.
That rig'll blow anything out of the water you can get from any OEM at that price easily.
Now I'd dig up a guide to build a PC but I don't have time to but I'm sure you can find a recent one. Honestly, building a PC is like a slightly more complex version of Legos but one where you can't put the pieces in the wrong slot (if you need to cut anything, you're probably doing something wrong!). Also, all the cables you need usually come with the power supply and motherboard anyways.
Nice setup.