They are well hidden. Search for .dbx files and they should reveal them selves.
They should be in C:/Documents and Settings/[account name]/Application Data/Identities/[Long alpha numeric name/Microsoft/Outlook Express
Application Data folder may be hidden unless you go into Windows Explorer - Tools - Folder Options Select the View Tab and select the radio button for "Show hidden files and folders".
Long alpha numeric string is a unique identity. If more than account is set on the computer you'll have to look in all the Identity folders to find the right folders with .dbx files. These can then be copied to the same appropriate place on the "new" PC, but will overwrite any newer ones on that PC.