Mac - partition question

Hello,

Long-time pc user who is trying to learn about macs as fast as possible :-)

I'm supporting a user who uses a mac, and who partitioned it in order so he could

run both Windows, and Mac.

I haven't been able to obtain info on how exactly the user partitioned his mac, but

however it was done, it appears that they didn't do it correctly as he as plenty of

hard drive space for the windows partition, but has run out of space on the Mac OS

side.

Is there a way that one can undo, or re-partition the hard drive without having to

redo everything, or is it like Windows where, if you reformat/partition you have to

back everything up as when you do, you'll wipe the drive.

Hopefully that all makes sense, but please let me know if there's any additional info

needed.

Cheers,

Jim