Newcastle,
Whereabouts are you located? From your name, western PA has a town called New Castle. If that is your location, Apple has two Apple stores in Pittsburgh and there is an Apple franchise dealer, Mac Outfitter as I recall the name, a few miles north of the I-79 - PA Turnpike exit (East side of road) on Rt. 19. That's the Cranberry (Mars) exit. You may want to visit an Apple Store AND MacOutfitter.
If you are not in western PA, find the store locations nearest you from:
http://www.apple.com/retail/
Remember also Apple, via its web site store sells factory refurbished systems with a new system guarantee for a reduced price compared to new systems. The available machines can change frequently so, if you are considering this option, check frequently.
Another point is recycling your old system. If you do not intend to keep your old system, Apple and some of the PC manufacturers offer free recycling service. If you do recycle, you may want to be sure that your hard drive is scrubbed of any personal data you don't want someone else to see. Things like Bank accounts, charge cards, purchase info, e-mails etc. come to mind.
Also, if you buy a MAC, also purchase one of the books available from a number of sources, to help you learn the full potential of your system. It has been my experience that far to many computer users, both Mac and PC, do NOT even realize, much less use, the full potential of the system(s) they purchase. There are many, many things that you can learn from a book that you may never find by simply blundering around with your computer. Check out a few bookstores to see which publication gives YOU the fullest and easily understood information about your operating system (OS X 10.5, Vista, Linux). It may cost up to $40 or $50 dollars but it might just be the best investment you could make to enjoy your new system.