Question about upgrading pc.

I got a Radeon 9700 Pro for Christmas ( ) , but the rest of my pc is getting old. i have a 1.1 Pentium Celeron with 256 ram. What i wanted to do was get a new processor, but I will need a new motherboard (I got one of those pre-built compaqs).

I am wondering if I could buy a new motherboard and cpu and use the rest of my hardware (cdrom, hard drives,etc...) with it. I have never installed a motherboard or cpu, so I'm pretty much in the dark on this.

I am hoping I would be able to use my hard drive on a new motherboard without having to format them and lose everything. Backing up is such a pain. I have 2 hard drives, if it matters.

Also, while on the subject, what motherboard/cpu do you reccomend? And are there any books that you reccomend I read before I do this.

I will greatly appreciate any help you guys give me. This is my first post on this board, and I wasn't sure where to put this, so excuse me if it would be better suited for another board. Thanks in advance.