Upgrading a cheap computer

[kjander]

I got day after thanksgiving door buster computer last year for $200 bucks and was wonding about the feasability to upgrade the computer.

I pretty much want to start a new build but salvage the operating system, case, CDRW/DVD drive, hard drive, power supply, case and RAM. So what i will have is an eMachines midtower case with CDRW/DVD drive, I have a sony DVD burner, a Ge Force AGP 128 MB video card, Western digital 160 with 9200 RPM. I would like to get a new mother board and cheap P4 processor with HT or an AMD 64 to go with this stuff, and then upgrade to 1.5 gigs of RAM Is something like that possible?

Does anyone have any advice as to how to do this as cheap as possible.