Does Dell Inspirion desktop T660 support 5GHZ wireless

I have a Dell Inspirion T660 and I am having issues with getting advertised Cable service download speeds with their router. The cable company says it must be that the computer isn't set up to run with 5GHZ speeds.  They didn't advertise that to get their advertised speeds that 2.4 GHZ channel wasn't capable of those speeds or that a user would have to change hardware to get those speeds. Is this PC capable of using 5GHZ or can it be upgraded to do so?    

Thanks

Ron