I had to do a restore of a backup after having the firmware upgraded and it RAN OUT OF ROOM! Presumably the phone was pretty full when I did the backup and the new R2F software is bigger than the R2D.
Anyway, you can set WinXP to always open .ecs files with winzip. Trouble is, I deleted a whole bunch of unnessesary files (Opera cache files) to free up space (using winzip) and then Backup/Restore couldn't open the backup file - must have broken a parity check or something. Pity, would be very useful if you could.