Your bike should be fine (unless you have a really long commute). Mid 80, early 90's steel framed mountain bikes are amongst the best commuting bikes out there. They are comfortable & virtually indestructable. As you get better at commuting, you may look to make your bike faster. The best way to do this without spending a lot of money is to replace the knnobby tires with slicks. As long as you aren't going off-road on the bike, this will make a pretty noticable difference in your commute, but it's certainly not necessary, epsecially at first.