Problems with WinXP Pro

Alright, I'm alright with computers but not the greatest so bear with me just a little bit here.

I recently installed a hard drive on computer and installed Windows XP Pro on the machine.  So far, it's been running fine, it boots up quick, it works great...but my problem is that it doesn't recognize any of the hardware...so I don't have any sound.  I only found this out when I tried to play some music using Windows Media Player and I got an error prompt saying that no soundcard was detected.

What can I do?

>>8

I've never used the product key before.  The machine came with the  OS already installed...and the only piece of hardware that I've changed is the HD...because my old one died.  This pisses me off more and more and makes me want to install Linux, but then I won't be able to use programs that I enjoy using in Windows like WinAmp, Adobe Photoshop 7, Jasc Paint Shop Pro 9...just to mention a few. :\

Wow, Microsoft contniues to suck ass.  And to top it all off, I have to pay them AGAIN to use my own product key...:\