What Ger21 said.
Mach3 is a CNC Controller application that reads CAM files (G-code) and generates signals to send to your motor controller to move the axes (X,Y,Z,etc.) of your CNC router, lathe, plasma table, laser cutter, etc.
The CAD program is used to make the initial drawings of what you eventually want cut. The CAM program is used to translate your CAD drawings into G-code that's used by a CNC controller, such as Mach3. There, I think we've come full circle now.
Ger21 mentioned SheetCAM and G Simple. You may also want to check out CAM-BAM, BobCAD-CAM, ArtCAM, EnRoute, and my personal favorite, Vectric VCarve Pro.
Don't take my word for it though, check out all of the web sites, download and try out the Trial Versions, read through the threads here and make up your own mind. What works for one person, may not work well for you. I don't know your budget but some of the above applications are quite pricey. Make sure you try as many as you can, before making a financial commitment.
What CAD program are you using now?
IHTH rather than confusing you more,
HayTay
Don't be the one that stands in the way of your success!