I've been with Roots Magic since Version 3. I currently am using RootsMagic 4 and am considering upgrading to 5. 5 has just been released and I'm waiting to see what bugs it may have before I upgrade. I go here daily to check out what's happening: http://forums.rootsmagic.com/
I chose RootsMagic because of ease of use, its many reports and the Shareable CD you can create to give your family...
BTW I am using a Dell Windows 7 64-bit Desktop computer and often use flash sticks and DVD's to save my data.