I too have been a macman since 1996, and still have my powerbook (running strong) since 1998. My wife and I fully converted last year. If you don't need a laptop, I would recommend the imac desktop (http://www.apple.com/imac/). Slim design, super fast, lots of memory. Also bought a huge external drive to run weekly backups via the time machine application. I just can't believe how much memory is in these things nowadays. We have movies, thousands of photos, and over 900 cds on and its still got lots of room.
As for viruses, there are definetly less viruses out there for macs than pcs. However, its because of sheer numbers. Essentially hackers get more bang for their buck developing viruses for pcs than macs. As soon as the % of mac users increases and comes closer to pcs, you'll likely see a surge in mac viruses (as explained to me by a tecchie).
Also, as for pricing, mac's are standard priced. You won't see much difference from the mac store vs. future shop vs. westworld. Personally, I've enjoyed the folks at westworld as they know their stuff and aren't as busy as the mac store so you get more personal time with them.