problems with leopard

I just installed leopard on my ibook g4. First I had to install extra ram. That worked and the leopard install worked. The problem is that there is now very little unused space on my hard drive. I had about 10 gigs before leopard and now I only have about 4 and it's slowing me down. I went to finder and looked at everything listed in the hard drive and found how much space it uses and came up with a total of about 30 gigs so i should have more room on the hard drive than the 4.8 it's telling me is there. Are there things that I can delete and where is the rest of my space? Is the panther taking up space needlessly? Do I still need my os 9 on the hard drive?

Did you erase and install or do you have two operating systems installed? When you mention Panther sounds like two which is not a good practice have the two on the single drive.

how can i tell if i've got two operating systems on my hard drive?

If you did an Archive and Install, this type of installation moves existing System files to a folder named Previous System, then installs a new copy of Mac OS X.
If you have a "Previous System folder", you can delete it.