Obviously you are/were not following my advice to use an extra partition for data
Meaning, you should install programs not in C:\Program Files, but in (D:, E: or whatever Partition for Data).
A relatively easy way around some data shortage would be to move "My Documents/My Pictures/My Music" to your Data partition.http://www.mydigitallife.info/change-my ... and-vista/
Furthermore, use a program like CCleaner, to empty your (probably overstuffed) temp files and IE/FF caches.
You can happily delete all the $NTuninstall... files, along with all the KBxxxxx.log files from your Windows directory.
That should give you a quick breather.
With programs like GParted or Parted Magic you can expand existing partitions, but you need to make space for expansion first.
Assume you have C (20GB), D (150GB), and E (150GB).
You need to create 30GB extra space for C between C and D. Use the partitioning software to 'shrink'/resize the D partition from 150GB to 120GB, leaving space BEFORE the D partition.
When done reboot
(this is important, do not skip!).
Now 'expand'/resize your C partition, using the empty space that was freed up above.