Installing new hard drive - thoughts?

[dukemagic]

I'm about to back up everything I want to keep onto an external hard drive (which I already have / have been doing) and taking out my current hard drive (3 years old, 160 gigs) that I've never had to reformat since I got it, and replacing it with a larger hard drive (160 gigs, 16mb buffer rather than 8mb).

The hard drive is only 60 bucks off of newegg, and my computer has been steadily getting a little slower, I think from age and from all the random stuff I have on there (I've never had to wipe my hard drive clean, so this is 3 years worth of random crap building up). It's taking a LOT longer to start up than it should, and for the amount of RAM and such I have, it's slower than I think it should be (Dell Dimension 8400, I upgraded the RAM to 2 gigs, 3 ghz processor, upgraded the video card a while back to ATI All-in-Wonder x600 - yes I know this isn't anything amazing, but it should still be decently fast, no?). I've done a lot of virus and spyware checking, so I think I'm as clean as I can reasonably get it, without doing a lot of stuff that's way beyond me. Does anyone have any thoughts?

Here are mine:

a) computer will be cleaner and faster
b) will still have old hard drive in case i mess up something
c) replacing hard drives is easy, right? just take out the old one, put the new one in, make sure the computer recognizes it, and then install windows and start over new

I'm a little worried about reinstalling the programs that require a password (Pokertracker, PAHUD, iTunes songs, etc) and carrying over all of my emails (I have thousands of emails I want to keep) and hand histories and stuff. Has anyone does this recently and have any thoughts to share? Thanks.