yes and no. surface speed is jus that, the max speed between cutter and work in say feet/min, and changes with material and cutter. spindle speed is determined by the surface speed + all other factors (setup etc) in theory if its hss into mild steel the surface speed is the same but there's other factors, how heavy is the cut, how rigid is the setup/machine etc. I'd run a slitting saw slower, but for set up reasons not because the max surface speed has changed consider getting a copy of machinery's handbook, and/or google maching feeds and speeds, or some machining texts its no problem answering some questions but you'd benefit from a deeper understanding as this stuff is core to metal working
here's a start
http://www.bitlady.com/speedfeed.php
here's another that i like cause I knew Robert
http://yarchive.net/metal/empirical_feed_rates.html
Robert Bastow "t-nut" was one of the most knowledgable and helpfull metal workers on the net imo, he's no longer with us but googling sometime churns up some of his delightfull tidbits