the 6MB version will let you browse. The other 11MBs are:
* Windows Media Player and other graphical stuff (not really needed... I mean, who have stumbled across an AOL-Propietory graphics file yet?)
* Outlook Express 5 (Works a lot faster, claims a friend of mine who installed it)
* Internet Core Fonts - If you have IE4 you probably don't need these.
* Additional Fonts - More fonts!
* MS Wallet
* MS Java VM Machine - the thing that lets you run Java Applets on your browser
* IE5 Help
* Language Auto Select
* Web Folders, Web Publishing, etc.
A lot of junk that you probably don't need. And when you do need it, you can download the components on a need basis.
About the ISP supporting IE5 - I think it's more in the Technical Support perspective, rather if IE5 will work with your ISP.
I still have a grudge against Netscape... I tell it to give me a frame that's 150 pixels wide (or x pixels high), and it never gets it right. Never.