That's a good point re: hard drive - for some reason I took that as the processor speed. Der. Agreed that it's 99.9% likely that you're not using XP, in which case you're starting to limit yourself to hardware and software support (I say limit as there's still PLENTY of options, but you'll have to take care when purchasing and read the small print
).
If that is the HDD, I'd also "guestimate" (haven't used that word since school) that you've got a Pentium II equivalent. Not really the best starting point for video editing.
This, combined with your small HDD, suggests you might have to invest in some serious upgrades (essentially a new PC).