A few comments:
For one, memtest can lock up but continue to count how long the test has been running IF the memory controller isnt working up to par. There is a text field that tells you how many passes the program has performed if you've gotten past 2-3 you should be alright. If you ran it for 17hours and it never said it completed 1 pass, I'd say memory controller errors!
If you get memtest to pass try running a Drive Fitness Test, most manufactures have one you can download from their site, if yours doesnt Hitachi (sp?) has the best univresal DFT in my opinion.
If your hardware passes both of those tests make sure you dont have any RAID options set in the BIOS make sure all options are set to SATA or (E)IDE you might have to look around for different controllers. Because if you have one enabled and dont know it, you obiviously didnt install the RAID drivers when installing windows which will make things wacky.
You shouldnt have to disable boot from CD just change the boot order to have the unit boot from the harddrive first.
If you've done all that and your still erroring out I'd tell you to take it to a local PC shop and see if they can install windows using one of their store use cpu's(if they're a good service shop they'll have SOMETHING that will fit your socket they can throw in there to do the install) if they can get it to go through, pop the 4400 (just swapping out a CPU wont get you, your 7 strikes against windows so dont worry about having to reinstall or reactivate) in and run a few stress tests and see if it errors out in a windows environment. If it does you might be out of luck. If it doesnt then more power to you!