MyStars! is crippled (# of stars shown, etc.) unless you pay $20. There are better programs for free.
Hallo! Northern Sky
http://www.hnsky.org/software.htm (which does include the whole sky), runs on M$ boxes or under WINE in linux
Stellarium
http://www.stellarium.org/ (prettiest graphics) linux, Mac, M$
Both have huge catalogs installable for free, and you can customize your own object catalogs.
KStars if you run linux. Expandable object catalogs, will drive your telescope if you hook up a compatible drive. Free, and you have the right to get and modify the code if you want to.
There are others, but these are all free and comprehensive.
I have friends who like Voyager on the Mac, and it also runs on M$ Vista, but they have their employer pay for it. See Carina software.
Celestia is also very cool, and lets you fly around in space. Free. You can write scripts for this as well, but it's not so much a traditional sky map program. linux, Mac, or M$
Lee