Just go to the 'C:\Windows' folder & right drag the 'Application Data' folder to another drive or another partition, then click 'copy' in the right click contextual menu that pops up.
Then after you have gone through the Format c:/install windows routine, you go to the new 'C:\Windows\Application Data\Identities' folder & write down the name of the folder inside (or 'copy' the name to the clipboard). It should look something like this, '{E4C03280-ACD1-12Y4-973S-865EDE60G825}' (except the odds are about a million to 1 on that the numbers & letters will be different.
Now go to the old 'Windows\Application Data\Identities' folder & give the folder inside it the same name as the folder inside your new 'C:\Windows\Application Data\Identities' folder.
BTW, when you creat your new internet account, make sure you give yourself the same name in 'Outlook Express' as you had in your old 'windows' partition. Otherwise you'll have to rename your backed up old 'address book', inside the backed up 'Windows\Application Data\Microsoft\Address Book' folder, to match your new 'Outlook Express' name, otherwise you'll have to creat a new 'Address Book' all over again.
Now right drag your old '\Windows\Application Data' folder into your new 'C:\Windows' folder, & click 'copy' in the right click contextual menu that pops up.
Now open 'Outlook Express' & it should look just like it did in your old parition, except the appearance will be in the MS default mode.
I learnt this routine through the scientific method of trial & error, so there's probably a better, easier & quicker way of doing this if you can be bothered finding it.