microsoft IAS vs Cisco content switching

I need to advise a customer of mine on these two overlapping if not competing technologies.

not sure on the speed comparison, I assume the Cisco one is faster being a hardware company. MS cheaper.

Any experience with either technology. Therequirement is caching and pre-storage of web based content as well as information for other apps.

Also does ISA or any other MS product support blending of TCP sessions like the Cisco one. Ie; giffs from local cache engine and dynamic data fromdatacentre in wan core?