It's not often we claim anyone back from the dark side, so good call there!

It might help if you give a rough outline of what type of games you plan on playing, are you looking at massed battles with a high figure to man ratio, or are you planning on skirmish type games?
As I've not quite reached the age where I can't remember being 15, I recall that I had some very grandiose and unattainable plans re my gaming, which oddly haven't seemed to happen. So maybe you might want to avoid that route and give some thought to what you realistically will be doing.
I'd hold off spending your cash until you've decided on what you want out of a game
Free Wargames Rules has some good, not so good and some downright awful rules for nothing, so it's worth a root through for a start.
I don't know what you got from Black Cat Bases, but
Wastelands forum hosts a set of rules for post-apocalyptic/near future games that might be usable. I've heard good reports about them, but haven't used them myself.
Napoleonics or an all singing and dancing set of rules I can't help you with, sorry.
