I installed the 4.2 upgrade and it trashed my blackberry. (two blinking led). I was able to bring it back to life to the default (new) state. Before installing I backed up but it does not see the file. Where are the backup files kept on a PC??
The default location for the backup saves is your "My Documents" folder if I am not mistaken. As amazinglygraceless stated, the easiest way to find them is to do a search on the PC. make sure you pick the latest copy to keep all of your PIM data up to date.