http://www.amazingcharts.com/ub/ubbthreads.php/topics/22397/Slides_from_ACUC_on_Backups#Post23669sbc,
Go to this link and download my presentation. Make sure you read how to do it and read the comments on the right hand column. You have the right idea, but your program is not going to be enough. Good backup programs range from $99.00 to well over $1,000 and more for small businesses. You want to think general to specific. Back up the entire computer first, then back up the AC folder in some capacity, then use your .enc files. Take one home once a week and maybe use offsite backup that is truly automatic.
To start, I would recommend two USB2.0 external hard drives and a program like Backup Assist if you have a server, if not, Acronis.
Not to brag, but I have 60 full backups of my server at any given time. That is six weeks of full backups times two different back up programs. Separate backups monthly and yearly. I can always go back at least one year and grab a file. But, you don't have to go that far. But, just get a little more robust than you are thinking right now. Don't forget. Is AC your only program? Do you have Medisoft or some onsite billing program?