There are several inexpensive editing programs to do some decent basic editing with a few premade motion effects like Sony Vegas, Adobe Premiere Elements, Pinnacle Studio, or if you have a Mac... Final Cut Express. Now if you are wanting to do some serious editing with alot of capatible programs and accessories I would look at Adobe Premiere Pro 2 and up for PC, or for Mac Final Cut Studio 1 and up. I personally like using the Mac for editing as it is alot more stable operating system without alot of the locking up or glitches, especially during rendering phase!!!
With PC you will want all of the RAM you can get, with a minimum of 2GB in my opinion, and preferably 3 to 4 GB at least. Also you want to get plenty of external hard drive storage to capture all of your footage to, etc. So get you a 500GB hard drive at least. Good luck and have fun!!