Yes, if you partitioned in Mac OS Extended you should be able to.
Open Disk Utility (Applications > Utilities) and go ahead and select your disk from the list on the left. You should see your hard drive and the two partitions under it.
Select the hard drive, go to the Partition tab, and you should get a box split into two representing your disk. To resize the partitions drag one of them smaller an the other bigger, or select them and change the "Size" value on the text box into their respective new sizes.
When you are done click "Apply". Again, this is just possible for partitions formatted as Mac OS Extended. The format should be visible in the Volume Information, right above size. It cant be changed unless you reformat (and loose all your data) so you would have to backup and "wipe" that partition if it's FAT32.
Time Machine, im pretty sure, works only on Mac OS Extended, so there shouldn't be any problem with that partition. If you don't work with a Windows machine too then theres really no reason why the other partition should be FAT32 (FAT is used for Windows compatibility) so really, you should drive into no problems ;)
If you need any extra help just go ahead and comment!
Hope it helps.