The install within windows always downloads the 64bit version of ubuntu if your processor is 64bit capable.
You now have two choices follow this thread
http://www.blitzbasic.com/Community/posts.php?topic=77778 and use the 64bit version of ubuntu
or
download the ubuntu 32bit iso, uninstall the ubuntu 64bit version ( it will ask if you would like to backup the ubuntu install ISO just say yes). Find the ubuntu backup folder, remove the 64bit ISO that is there and replace it with the 32bit version, then re-run the ubuntu windows installer.
And don't worry Linux confuses the hell out of any body the first time round (as well as the second,third,fourth,fifth,and on and on and on).
If you need to fine out which version of ubuntu is installed the open a command terminal (Applications->Accessories->Terminal) and type
uname -a
if any where it says x86_64 or AMD64 then its a 64bit OS. If it says i386/i686 then its 32bit. If it say SMP in the response it means that you have a dual core/multi-processor installed.