Nokia :: 5800 Getting More Memory Back On C Drive?

I noticed my phone going really slow, when I went into the c: folder on the included file manager of the phone it said I had only 3mb free space. After getting rid of bluetooth sis files in the messages folder and clearing the internet cahe I now have showing on drive c: free space of 23.2MB - good I suppose but I want to see if I can free up more space as the phone I believe does have around 80mb total (I know i should expect that system files of the phone will take up space but this much?) so anyway I suppose what I am is asking how I can free up more space as I cant see any more files I can delete on C: going through the inbuilt file manager and using windows file manager. I suppose I could use an app like y-browser or active file manager or whatever the app is called but its quite time consuming doing it through the phone, i would rather if anyone knows of an windows xp application where I can link up my Nokia 5800 by USB cable and run an XP app which will hunt out all files on C: including hidden/system and other files. i know I am going into dangerous terrotory of seeing system files and deleting them and bricking the phone but if I could see some hidden pictures and sound that I dont use and they are not tied to system files then I could delete them and get some more files back on C: - or has anyone know what else I could clear on the phone to give me back more than 23mb?