Here are some zero-money solutions:

• Inno Setup - Something like Installshield. Quite powerfull.
• Nullsoft installer - used for WinAmp and lots of other stuff. Simple minded but seems to work for many people

I have only briefly used InnoSetup and never used the Nullsoft thing, so I can't really vouch for them. The InnoSetup thing was pretty painless though.

Update: Wassercrats spotted that I put the wrong URL for Inno Setup in the node