generally speaking, if you want a Win XP OS only partition, it should be over 8 GB. That will leave it plenty of space for TEMP files, other Windows stuff (background services that have to run in order for the pc to operate efficiently and take up loads of memory for some reason). The Operating System files & folders take up more space than what you see.  Also bear in mind that any temporary files created for renders and projects for Poser are stored in the base directory of none other than C:/ drive...  The other temporary files folder you are looking for is the USER one.
so it would be C:Documents and SettingsUSER NAMELocal Settings (mind you will have to select the show hidden files and folders option and uncheck the Hide Protected Operating System files option as well in your Windows Explorer Folder Options menu).

And don't delete hidden files located in system32 folder!!!! You may end up with a pc that won't boot!!

Glad you managed to sort it out by renaming :D