Basic basic cable has ESPN & ESPN2. That'll be maybe $40 a month max, if that, which is a HUGE savings over the bigger packages. None of the sports channels are broadcast over the air, so any antenna will not help you with that. If you want to keep the sports channels, you'll have keep cable of some sort. I have Comcast because nothing else is available in my area yet and I had years of bad issues with satellite. Plus, if you call to cancel, they'll likely offer you some major deal to keep you for another 6 months--like same service for introductory/new customer price, etc.
Antenna-only will get you the local channels (ABC, CBS, NBC, Fox, WB and maybe PBS and a couple other low-budget stations).