4600/DVD+RW

I am looking at purchasing a Dell 4600 and I was interested in building my own system.  When considering DVD/CD ROM options, I didn't see a choice for a combination of CD-RW and DVD-RW.  The option I was considering was a dual drive that was listed as a DVD-ROM and DVD-RW.  Does this allow me to burn CDs as well or do I need an external burner to work with the computer?  Is there a combination available for this computer?  Thanks for sorting out my naive-ness.