Re: Can I upgrade my laptop?
Let me start by saying I would advise against this. For most laptops, it's okay to upgrade ram, but beyond that, it's tricky business. I've ruined at least 2 despite all my experience with desktops. As a matter of fact, I've had a 100% success rate with desktops (building, dismantling, upgrading, etc.) and close to 0% with laptops. People think experience with desktops makes them able to work well with laptops, but that's usually not the case, as I learned the hard way...
I'm not familiar with your particular laptop, but I do have a Presario C700, and I wouldn't be caught dead trying to do anything more than upgrading ram. With all that said, you may find some help here http://repair4laptop.org/disassembly_compaq.html should you decide to go ahead and tinker.
I don't think anything there is exactly what you're looking for, but there should be something that's at least similar to get you started on the right track. (You don't really want to replace your motherboard do you? That sounds like a suicide mission...)
My main system: AMD Athlon 64 X2 3.1Ghz, Nvidia 8800GT, 4GB RAM, Debian Lenny/Windows 7 dual-boot. My laptop (Compaq C700): Intel Celeron 1.7Ghz, Intel X3100, 1GB RAM, Ubuntu Lucid.