If you want to go Mac, then to a large extent you just need the data off of your Dell drive, and to do a separate installation of VMware Fusion or Parallels. As others have pointed out, you then need to do an installation of Windows on the Mac. You can then run Windows in a window on the Mac for times you need it.

What you should do is to create a separate folder (directory) on the Mac to contain the files you created (that is, not the system or program files) from the PC. You can then set it up to get at this directory from both Mac and Windows. Especially if you install Microsoft Office for the Mac on the machine, you'll be able to get at most of your files in Mac mode and you'll get better performance that way. For those remaining things that you need Windows for, you can boot up Windows in Parallels or Fusion. However, you may find over time that you do this less and less frequently.

I suspect that you can make an appointment at an Apple store to have them show you how to do this. There are also data recovery services that can get your data from the Dell's drive onto a portable USB drive if you have no other options.