I'm relatively new to the macworld, having purchased my first 13" MacBook Pro 2.53GHz, 4GB RAM, 250GB HDD, with Snow Leopard v10.6.2 about 7 months ago. I can definitely say that I'm extremely impressed with the performance thus far.
I've kept it pretty clean with a minimal amount of applications installed and have limited myself from experimenting too much to avoid any problems. Is there anything that I should be doing in terms of maintenance such as period reformatting or anything of that nature?
You need to let go of the Windows mentality. "Periodic reformatting?" That gets a big laugh round here.
I'm glad you are enjoying your Mac, but your days of spending lots of time thinking about how to maintain your computer are OVER. Yes, the Mac works best with a small amount of maintenance, but it's nothing like what you're used to from Windows.
As others have said, your best "insurance" against problems is a backup. Personally I keep TWO backups, both automated, since external hard drives are so ridiculously cheap these days. One is a Time Machine backup, the other is a "clone" backup (using either
SuperDuper or
Carbon Copy Cloner). Once set up, both take care of themselves automatically.
Beyond that, I generally suggest the occasional (as in "once a month AT MOST") use of either
Maintenance or OnyX (the former is just a simplied version of the latter), both free. There's another one I'm presently investigating called
IceClean that seems nice too.
For people who refuse to do regular backups or otherwise don't take care of their machine, I also suggest buying a copy of
DiskWarrior. It's a one-trick pony but it does that one trick EXTREMELY well, by providing a bootable DVD with the one tool that is likely to fix a severely corrupted hard drive well enough to recover valuable data. I still use it once a year or so to "repair" the "creep" of directory fragmentation that occurs on a busy machine like mine, but I have to admit that for most users, if you follow the suggestions I've outlined above, you're actually pretty unlikely to need DW.
Speaking of fragmentation, "defragging" is a constant concern among Windows users, but is practically a non-issue on the Mac unless you are routinely working with extraordinarily large files (editing HD video all the time, that sort of thing).
I tend to swap out my machines (or at least the hard drives) every 2-3 years so I've not really had to worry about this, but people who keep their hard drives for a longer period should probably do what I guess you would call a "periodic reformatting" every couple of years. Basically the procedure is to clone your hard drive to an external, boot from the clone to make sure its good, then zero out the original boot drive, then clone back. You can also purchase something like
iDefrag to do on-the-spot defragging for you if you prefer. This has the effect of "optimizing" the boot drive, but I just want to emphasize that Mac OS X has a limited version of "defragging" built right in, so this is NOT something you should need to do very often across the typical life of a machine or HD. Most Mac users never do it AT ALL.
In summary, backups are your first line of defense against problems, and very little maintenance is needed beyond that -- but its a good idea to DO that little bit of maintenance every now and again.