Which component is faulty?

Hey guys I built a new system about 5 days ago on some used hardware and some new stuff. I got a bunch of (non random) BSOD's when I tried to reformat my hardrive or try to reinstall windows XP. I went into the BIOS and reloaded failsafe defaults and thought I had fixed the problem when all of a sudden when windows was installing certain files to my hardrive it would give me errors with messages like "an error has occured when trying to install <insert file name here>. press enter to try again and press ESC to skip this file." I got that error with about 50 different file names and had to skip every single of of them. After it was done installing the files that DID work I got a BSOD with the error message "PAGE_FAULT_IN_NON_PAGED_AREA". I thought it was either my memory or my hardrive causing the problem and since I had formatted my hardrive there was no OS on it so it would be difficult to run any tests on the hardware.

My cousin told me about a free software called ultimatebootcd which had a lot of diagnostic tools on it and didn't require an OS so I downloaded it and burned the .ISO file to a CD and booted from that. I ran Memtest86+ on it for over 15 hours without a single error so I don't think my memory is the problem, but could my RAM still be bad even though it passed memtest?

Right now I am running a hardrive diagnostic to test the HDD but is there any chance it could be the DVD burner or the windows installation disk causing the problem? Unfortunately I don't have any spare hardrives to try installing windows on but ill probably run out to microcenter and pick up a cheap $40 HDD to use.

My new hardware:
Intel C2Q Q9400 @ 2.66 GHz
OCZ 4GB DDR2-800 ram
Gigabyte EP43-UD3L motherboard
Antec nine hundred case

My used hardware from my last build:
Western Digital SATA 320GB HDD w/ 16mb cache
Corsair TX750w PSU
XFX 8800GT alpha dog
Lite-On DVD/CD burner

OS: Win XP home edition SP2 32-bit