Just in case anybody finds this thread in a search...
I have put a lot more time into this and have posted some findings
here.
Basically,
you need a hacked (jailbroken) phone to make any impact on this low-c: - space issue. If you haven't then just about all you can do is a factory reset and start from fresh, carefully setting the Ovi Suite preferences to install to E: rather than C: for example.
There are also hacks e.g.
here which can be used to recover a lot of space. Deleting the unused language support files would recover close to 20MB, but unless you use another hack to make the Resources directory accessible over USB (on a PC) deleting the hundreds of *.rxx files (but not *.r01 etc) is going to take some time using a phone file browser (ActiveFile is the only one that works under Symbian Belle and sees everything on the phone).
Nokia have not by any means given up on Symbian phones. The Pureview phone (808?) is amazing. And they are having no end of problems with Windoze Mobile (as one would expect).
Nokia are going to have to fix this issue because once you get below about 60MB free space on c: you cannot install any more updates
And to arrive in that situation, all you need is for somebody to send you a dozen large-attachment emails
The best hack is the one which causes emails to be placed onto the e: drive.