I must give credt to MikeB from the Macbites website for making me think a little more about why I was getting a slow login. Extract below from a reply I made on the Macbites website after MikeB had given me some suggestions.

I have other user's at present I'm really the only one who uses the Mac regularly. So I tried one of the other user's and after the initial boot up for Leopard, I did another login and it took 7 secs from the user screen to usable desktop. That also confirmed that the partitioned 500 gig hard wasn't causing the problem, this I had already checked by disconnecting. So I went back into my account and guess what app started up, iTunes, hang on I thought I'd logged out fully, so I went into my login options and there were several login options that were obviously iTunes connected, so I got rid of them re logged in and from user screen to usable desktop 12 secs, that'll do. so although you didn't directly help you made me think a bit more. Good man as I really didn't want (or think I should need to) do a clean install.

Cracking smiley faces all round again..... ;-))