What will I get when I hard reset?

[Spookmeister]

I have been having problems recently with my device - including using Activesync ( I have followed all the walkthroughs there are and cannot use this app). So I thought that I'd do a hard reset.

I know this is a pretty extreme measure but I don't know what I should be backing-up. Because I was given this handset I don't know what applications were "default" and what were user install. Is there a way of finding out what is what?

Also, I don't have any original "getting started" discs that I might be expected to have.

Thanks in advance.

S.