Your 98 pc might run XP but you won't be happy with it. It will be slow as a snail! And you probably won't be able to record any video that is worth watching. Your ram(memory) really needs to be bumped up. I would suggest at least 1 gig if you are going to capture video.
Hard drives are fairly cheap now a days. You can use
www.pricewatch.com to find one for your pc, which is probably IDE interface. I have a 40gig hard drive on my pentium 4 machine with 1 gig of ram and does fairly well. But it all depends how much video your going to be recording before you can review it and delete the clips you don't want. If your not going to review for a while that I would suggest a bigger hard drive.
That being said though, one needs to realise that recording video can eat up your hard drive space quick. Depending on what kind of settings you use.
One thing you can do is get the model number of your (Hp) I think you said and go to hp's website and check the specs on it. It should tell you the max amount of ram(memory) and what kind that can be put in your machine. Again, you can go to your local used pc store or to
www.pricewatch.com for memory as well.
After looking all this up you might want to compare "upgrading verses used xp box". I personally think I would go to a used pc store and see what they had to offer. If you do choose to buy a used pc make sure you either get the actual XP cd or recovery cd's for it. You want to be careful about the XP cd's though, there is a lot of counterfeit cd's out there.