Windows 2008 TS gateway and app publishing will do the same thing
If you're after 2 factor auth on a budget, look at Deepnet security - its superb, very cheap and a lot simpler to administer and set up than RSA
Our intranet is accessed via the internet as I/we use it for our job system and various important files, works very well.
Just remember to set it up so they cant browse externally.
We did something similar and found people didnt realise it was a remote app and when they were finished on the intranet, they carried on browsing with it...