Dear nissan,
Here is what your mother board will take:
HP.com:Lucky for you a great upgrade will not cost you a lot of bucks.
Your specs say you are upgradeable to 2GB mem but Corsair says 1GB. Anyway, check you manual. Here is a memory upgrade, you will need two of these:
ZipZoomFly.comAs for hard drive, I go with Western Digital, but you really need to match the drives. Meaning, 60gb with 60gb, 80gb with 80gb, and etc. Zipzoomfly kicks Newegg's butt in some pricing. Check both.
Now a sound card. Go with Creative labs. They have a great customer service and the best sound card on the market. Expensive for the best but they have some great lower price models that sound just as awesome.
Be careful to turn off you on-board sound before you install you new sound card.
Hope that helps,
junkdk