RAM and Sound Card questions

Okay, so I bought my first Mac the other day:

PowerMac G4 533mhz
256MB RAM
13 Gig Hard Drive
OSX 10.3

So, my questions:

Can I throw any old PC133 RAM in there? I've got some from an old PC of mine...
Also, will PC100 work?

Can I toss an IDE hard drive in there?

Can I use a PC sound card in this thing? The whole "no audio input" thing scares me.

Any good PC-133 memory should work. PC-100 won't.

A sound card will require Mac OS drivers (which few companies provide.) You might be better off with a USB audio input, like the iMic

Any IDE hard drive will work, up to 128GB. (Drives larger than 128GB will require a separate 48-bit IDE controller)