Make your Recovery Disks first; test them by doing a restore from them.
You can use a third party partitioning tool like Partition Manager to reduce the size of your C: drive and then make your D: drive bigger. You can then store data on the D: drive that will not be erased during a system recovery. Or you can create another partition and drive altogether.
Two problems you need to overcome:
1/ Pressing F11 may not work after changing the partition sizes. Boot from the Recovery Disks, select "Run program from hard drive" and the recovery partition will be available for F11 again
2/ After recovery, the data on the D: drive will still be there but may be inaccessible. To get at it, run the following batch file (as administrator):
REM to see recovery disk on HP PCs
REM remove read only, system and hidden attribute from
REM all files and folders including in subfolders
attrib -R -S -H d:\*.* /S /D
REM Delete all desktop.ini files from all subdirs
del /F /S desktop.ini
To open a command prompt as Administrator, Start, All Programs, Accessories, right-click command prompt and select "Run as administrator".