I think you should stick with what you have for awhile for two reasons. First, it will help you decide if you can stick with it before you spend more $$$. Second, you will get an education about what you need and don't need (or want and don't want). After a few months or a few years, you will be able to make much more educated choices.

I used a Raleigh M-50 for commuting on and off for 6 or 7 years before I finally bought a cyclocross bike (basically, a road bike that has room for bigger tires). The M50 did just fine. I commuted continuously for about 6 months last year before I convinced myself (and my wife) that it was worth the upgrade.

Now, I'm a year-round commuter. I run 28's at 95-120 in the summer and 35mm Nokian studded tires in the winter. After taking my old M50 out for a few rides on bad roads, I loved how much better it handled the potholes. I'll probably put 32 slicks on my cyclocross bike in the spring.