Constantly losing free space in C:/ drive

[abhi123tri]

hi friends! please help me . i am in deep trouble of having my c:/ drive completely full(0 byte free space).i'm using Windows XP ProSP3. i've C:/, D:/ & E:/ drives size of 24.8 GB each.
i've performed many tasks -
Cleared my Recycle Bin
Cleared my Windows temporary folder
Removed many installed programmes
Cleared browsing data and history, cache and temporary internet files

but the problem is as it was.i'm also attaching an image of the files i've in Program files.
please tell me something about the files i've underlined, whether they are o.k. or not. if required i can give you extra info. about those files.But please tell me about those files and also suggest me what should i do to solve this drastic situation.
how should i get rid of this constantly decreasing space of my C:/ drive.

[Enriquee]

Instead of playing with those files I will recommend you to add some space extra to your c drive. What is the size of your hard drive. You can take some space from empty partition and add the same to C. For that you will need Partition Magic. This new version allows to merge two NTFS partitions, recognize drives larger than 160GB, supports Windows XP and allows you to partition disks External USB 1.1/2.0