I have written a converter that takes openstreetmap xml files and converts them to a binary runtime rendering format that is typically about 10% of the original size. Input file
Assuming you are using Windows XP, if you are only just over your memory limit and do not desire or have the time to rework the code as suggested above, you can add the /3GB switch to your boot.ini file and then it just a matter of setting a linker switch to get an extra 1GB of memory.