ok, i was lazy and didn't replace my chain early enough last year. i bought a new full suspension bike (Specialized FSR XC Comp) in March 2002 and then rode 3800km and 65,000meters vertical in the last year... without changing the chain.

then i "retired" my full suspension for the winter and rode my old hardtail to spare it from the salt. now that spring is here i got it back out and the chain is badly strechted - on the rear cassette you can see that it doesn't fit properly. so last week i bought a new chain and installed it and what i feared was true: the front chainrings are worn too much to the old chain: the middle ring skips and the small ring has REALLY bad chain-suck. so for my ride Sunday i put the old chain back on and could not use the middle ring b/c it skips, but the little and big work ok.

so, here is the question: how much do i probably need to replace?
small ring: yes - chain-suck with new chain b/c worn to old chain
middle ring: yes - seems to be worn badly b/c it's skipping with both the old and new chain

how do i know if the rear cassette is OK?

i read somewhere (i trhink Sheldon Brown's writeup on chainsuck) that for the small ring it is best to buy steel or even better titanium and not aluminum as it wears too easily. anyone have any comments here?

if i already have to replace the small and middle ring, is it best to replace the whole front set-up and buy all the rings and the crank together? (i.e. is it cheaper or just a good idea to replace that other stuff if the rings are so worn?)