Go for the cheapest 10/100 card you can find, unless you're doing something serious with it (building a server etc...)
There's very little difference apart from 3-com cards come with a lifetime warranty, and tend to have better drivers. You really won't notice the difference in day-to-day use.
I have an intel Pro/100, a 3com 3C905TX and three £10 accton cards at home, and there seems to be no discernable difference in ease of use or throughput...