A run-about bike for getting around town is always useful and can help make excercise just a normal part of your life, not a special event you have to dress up for.
Hybrid bikes do the job well enough, and have fittings for a luggage rack and fenders, so you can use them for winter riding, shopping trips etc.
I would second the advice to avoid suspension forks (and seatpost), and put the money elsewhere.
I would probably want to upgrade the factory tyres for a slick touring tyre of about 32mm. I use these for commuting, and for riding on trails. Kevlar banded ones will reduce the risk of punctures.
Cheapo bikes may also have crappy pedals. I like metal double sided ones (MKS make good, cheap ones), and you have the option to fit toe-clips which will increase your efficiency and safety. If you get in to longer distance road riding, you may want to go with a special cycling shoe/clipless pedal combo, but there is no need to go that way right now.
Budget for a hemet ($40 are as good as $140 models), gloves (to save your skin if you come off the bike), and some lights and reflective gear, eg a bright windprood jacket with reflective piping..
Shorts are only needed for rides over 10 miles, and jerseys are nice to have, but Ive done plenty of rides in T shirts.