Know just enough to get me in trouble

Have a PC, 300 MHz Pentium II, 256 MB of ram. Running Windows XP pro. This is a thrift store computer that I bought because the kids have pretty much taken over the one I bought new for the family a few yeas ago. I'm sure I'm not the only one who has had this happen! I managed to get the few problems it had worked out and has been great except for two things. The DVD player does not work. I think this is a common problem that happened when the prev. owner upgraded to XP pro. One post I read somewhere said you need a new dvd decoder or an mpeg codec. The ones I have seen available for sale seem to need a faster processer than have. Not the end of the world but it would be nice.

The second thing is much more important. I am running out of space in the 8 Gig. Hard Drive. I do have one I saved from another PC that I tried to get working but the prev. owner hacked the OS files apart in thier effort to clean out their personal stuff. It did boot but had lots of missing file errors. Scraped it when I got this one. I did save the Western Digital Drive. Model WD307AA. 30.7 GB. That was added as a second drive on the other PC. All I can find on WD web site is the specs. I know just enough to get me in trouble about these things. Have it sitting here and wanted a some advice before I attemept it. My Bios is set to auto Detect, Can install it with jumpers to set it as a slave, Should be able to use My computer to right click on it and format it. (Did add one this way to an older dell I had.) I don't think I really need to partition it? But I would really like to transfer everything from the 8 GB drive to this one and make it the master. Just have no Idea what the best and safest way to do this would be. I'm not cheap, just broke. Having two Daughters seems to do that. Any help on this would be great. Thanks David