I'm selling my N900 and I'd like to clean up my stuff from system partitions.

I've checked http://wiki.maemo.org/Updating_the_firmware regarding the N900 reflash. However, both links (to flasher as well as firmware) are 404. OK, I managed to download Flasher from the mirror (I suppose "Maemo Flasher-3.5 Tool for Fremantle and Diablo, installation package for Windows 7, XP and Vista (x86, 32-bit)" is the one for me - and I should do this in VirtualPC as I have 64-bit Windows 7). But where do I get the firmware image?

I currently run the latest CSSU stable release. Is there any easier way to do the clean up? The next owner is probably not a forensic expert, but I wouldn't want any of my old texts, contacts, customizations etc. to appear/exist when they use this gadget.