Need Diagnosis on MAJOR PC Problem

I'm running a adequate Pentium D @ 2.66 machine with 1 gig of RAM, 256 meg decent video card and about 320 gigs on 2 hard drives (300+20).

It's been working fine for about 1-2 years, but all of a sudden it's taking REALLY long to unrar files, move stuff along my various partitions and burning DVD's. What use to take about 30-45 seconds to unrar a a DVD ISO now takes 15+ minutes and over 1 hour to move/copy data across partitions on the same hard drive. Even burning a full data DVD takes approximately an hour,  about 54 minutes more than what it took a few days ago.

I haven't installed any new programs, in fact I've been uninstalling apps I rarely use and burning most stuff to DVDR prior to all of this. I run weekly spyware and virus checks and nothing's ever come up.

I have a few theories as to what's about to die.

I'm guessing it's either....

- the primary HDD (20 gigger one) that hours my XP SP2 OS
- the slave HDD (300 gig) that stores my music, games, movies, prawn
- RAM (reason why everything is now taking forever
- mobo or CPU - kinda doubt it, but who knows

Anyone know any sure-fire programs that tell me whether or not my HDD or RAM is dying or failing? I have receipts for my HDD's and would like to replace them before the warrantees run out if that's the problem.

Halp 4chan - any useful input would be greatly appreciated. Thanks.

OP again

As for other stuff, running mp3's in Winamp or watching movies thru DVD drive or playing games thru DVD-ROM yield no slowdown or freezing if that also helps. Browsing, word processing are also not affected.

try booting off a live CD.  if your problems persist, it's hardware-related.  if not, it's software-related.

if it's hardware, my guess would be RAM.  very possibly the IDE controller (read: mobo) or hard drives, but problems in those would likely cause significant data corruption/crashing as well as slowdowns.  back up your important shit NOW just to be safe.

Increadibly fragmented hard-drive. Probably not the problem, but the symptoms are similar, although not as extreme. I'll second the suggestion >>3 gave though.

back up everything, reformat. Most of the times its just slow because windows sux

Check if the hdds are running in DMA mode in windows (device manager), not that they somehow switched to PIO which is sloooow.
If it's not that try defragmenting, although your symptoms seem too extreme, still worth a try.
For checking the other hardware .. scandisk for hdds, try running prime95 torture test over night and see if you get any errors to get a _rough_ idea if there are any problems with cpu/ram/mobo (this includes clock speeds), or if you only want to test ram use memtest86 - although I doubt that cpu/ram/mobo really is the cause.