I have been riding for years, and have ridden in all weather conditions. I can say this about only a bike for transportation - don't do it. You may think that it will be cheaper, but if you compare overal costs per mile, a beater car is much cheaper than a sportbike - even a 250. Tires cost more, oil changes are more frequent, maintenance cost more, plus you need gear, etc, etc, etc. Lots of people have listed out the comparitive costs on the web, just do a search on Google.
If you are looking for cheap transportation, look for an old Geo Metro, a Civic, a Daewoo, or similar. It will be much cheaper in the long run. Don' forget, if you go with the bike, you need to get very good insurance - not just for the bike itsself, but also medical coverage, and short/long term disability. It's not practical for someone in college.