Tom's actually done a pretty good job on his own (he sent me his edited version so far)
It does raise an interesting question though about how much you should do to these old photos. I've been doing this work since the first home computers and the first photo editing software, and attitudes (including mine) have changed a lot in that time.
If you're going to do it it - the key thing to remember is you're trying to restore it to as near original as you can get it, and depending on the amount of damage, that's often nigh on impossible without the work you've done (a) showing and (b) having an obvious effect on the validity of the original image.
Interestingly, a lot of the valuable old historic photos which are shown on TV programmes are shown warts and all - the shots will have been scanned for preservation purposes, but they don't do restoration on them - even the ones requiring quite simple editing. The truth of it is that no matter how well the restoration is done, it will never have the credibility of that original old print which you can actually hold in your hand and marvel at the history it represents with all it's faults.
The problem is if you undertake this kind of work people will bring you old photos near to disintegration which are truthfully well past any meaningful repair and you should advise them accordingly. Often though it's a cherished photo of some loved one and they'll implore you to do your best - which of course you will, but never lose sight of the fact that your retouching work is judged from these results and the state of the original photo won't come into the equation.
The moral is store these old photos properly in the first instance - they're pretty well priceless.