One optin is to buy an additional H.D.D. and install it as a "Slave" Drive (Slave to the existing "Master" Drive). This gives you two separate drives to store Data on, and best of all you can keep the original drive as C: - with all the Data, applications and best of all - the operating system + drivers do not need to be reinstalled!!!
After the new slave drive is installed and configured (set jumpers, connect cables and verify settings in the CMOS BIOS utility), you will need to run FDISK to create Partition.
Need to work from a DOS prompt (boot directly to DOS by holding down the F8 key just before POST will end - then select #5 - Command Prompt Only).
Once at the DOS prompt ( C:\> ), type in the command:
Then press return (enter).
Choose the selection to log onto the other drive - I think this is #4 or #5 selection. Follow directions on the screen to create a primary DOS partition.
When all that is done, exit FDISK, the Reboot the PC to a DOS prompt again.
Now Format the drive. Do this at a DOS Prompt (boot directly to a command prompt). Type in the following command:
Format D: /U
then press return (enter).
The /U switch is an unconditional switch.
Answer the questions until FORMAT says everything is A-OK!!!, then Reboot the PC as normal (to Winders).
After all this baloney is done, you may Copy / Paste your Data Files to the newly installed Drive D:, or install new applications to that drive.
Don't move any applications - only your Data (pictures, text documents you have created, etc.).
Feel free to ask as many questions you need before taking this on.
If this sounds like too much, you could un-install which ever applications are not used, or delete Data files - or both.
Use the proper Uninstall routines for applications. Data files may be thrown away manually.
Another option would be to use a CD-R / RW drive, and save your Data files to a CD-R. This requires installation of a new drive, and if there's an existing CD-ROM drive you want to keep, the drives will need to be configured as "Master / Slave" like the H.D.D. did.
You can also use the Primary IDE Slave function on the H.D.D. - which may be a better option. Set the new CD-R Drive as a Slave to the existing H.D.D.
Again, let me know if you have questions on this stuff.
Last option would be to compress stuff. Either compress a section of the drive, or get an Archiving Utility - such as PKZIP, and compress your Data files.
.JPGs don't compress very much. .GIFs compress a little, but not much either.
.BMPs on the other hand compress alot! I put over 30 MBs of Bitmapped images on 3 floppy disks, using the highest level of compression with PKZIP.
Text files compress well, and so do many .PDFs and CAD files.
I guess the whole thing relies on just how far you wish to go, and are willing to pay.