Advice needed

So I bought my first Macbook about 2 weeks ago and I'm hooked. It's a 2.0Ghz, 3gb Ram, 80gb HDD, combo drive, and very clean for $500. One year warranty expires end of November. Now I'm the kind of guy that likes to have the latest and greatest, within my budget. So the question is do I spend $150 on eBay for Applecare for this one or put that money into a newer MB (not the newer alum MB) with a 2.4ghz, 160gb HDD, and Superdrive. I know the newer MBs have the faster 800Mhz bus speed and mine uses the 677Mhz bus. I figure if I bought Applecare and replaced the combo drive with a superdrive I'm looking at least another $200-$250. I can resell mine at $500 easy and apply the upgrade costs towards a newer MB. Is it worth the hastle? Will a newer MB be much faster to notice?

The new MacBooks have 1066 FSB. Does your current MB do all you need it to do? Why not upgrade the HDD later and buy applecare now? Either applecare will be worth it.

I can't afford the newest MB alumium. I'm just looking at the white MBs 2.4ghz ones. If I upgrade the HDD and to a combo drive will applecare cover those upgrades or will it void applecare?

I am not sure about the HDD but the superdrive won't be.

Can you not use externals? I never use my superdrive maybe 1 everything three months.

I guess I should just keep the one I got now, spend the money for applecare and be happy I got a good deal. I haven't used it all that much as I need to move a lot of my windows stuff over. I'm a field tech and need XP for utilities and such.