cracking car, loved mine to bits, possibly one of the best cars i've owned.
i have a set of 18" oz racing wheels sat in my garage which are a perfect fit for the s2000 if your interested. new tyres on and everything.
as for handling TCS came in after 2004 as standard, was an option on early cars from 2001 on but not many had it.
as for handling, 1999 to 2001 were a little snappy, but the 2002 to 2004 was the best model, had brilliant setup rev range went all the way to 9.5k after 2004 it was dropped to 8800 revs. the suspension was also softened out in 2004 but brought back to 2002 standard in 2006.
i had the hks exhaust on mine but it did drone at 3k but everywhere else it was amazing.
if you need to know anything drop me a line its not as big a widow maker as people make out, the handling is spot on; generally the reason people write them off is they think they are better at driving than they actually are. when it does slide it is extremely progressive and easy to hold. i drove mine in the snow and didn;t have problems, but it isn;t the easiest winter trnasport.
main things to check are the bushes, they tend to seize, and if they all need replacing your looking at about £900 of work. get the geo setup and its a minter.
i reckon you;ll enjoy it as well if she lets you drive it.