Sorry, I guess I should have included what I have done already.
I scan for viruses and spyware regularly. I run CCleaner on a regular basis along with defrag. I have already tweaked Vista to limit what I don't need as well as tweaking my startup files and services.
I have also reformatted the hard drive and saw no change in speed. In fact, it seems to be getting slower, which is why I'm hoping I could just get a newer faster HDD and that would suffice. I should add that this is my laptop that I use when I'm not on my desktop.