I have always used IE for my web browser, but now my ISP is recommending I switch to Firefox 3.5,?

Really comes down to preference. In my case, I like Firefox because to me, the interface is cleaner and more intuitive, the program is faster, and it isn't embedded as part of the operating system (separation of OS and applications makes more sense for security).

As for your ISP suggesting Firefox, you shouldn't have to do that if you prefer IE. Most websites support multiple browser types (IE, Firefox, Chrome, Safari, Opera, etc...). Likely someone at the ISP is just promoting Firefox because it is what they prefer. Unless your ISP has a site (maybe billing or account management) that only supports Firefox, use whatever browser you prefer.

this is probly some open source person trying 2 push somthing u dont need on u.

in my opinion ie is the best.

its fast, simple, doesnt require plugins 2 b useful, and its part of the operating system, making it generally have alot less random failures then open source stuff like firefox tends 2 have.

I like SRWare Iron for it's speed and I can use Fanboy's Adblock List which is the best. Iron is like Chrome, but without the privacy concerns...

i like firefox over explorer because its easer to use and save pages and overall its better in my opinion