384Kb is ridiculously slow for "high speed" Internet. Especially since there is two of you splitting the cost, get the 2Mb. What they're advertising is the speed of your connection, namely, 384 kilobits per second and 2 megabits (2048 kilobits) per second. Note these are kilobits, not kilobytes which is what your web browser usually reports. Technically to convert, divide kilobits/megabits by 8 to get kilobytes/megabytes. I've found as a decent rule of thumb, you can estimate what you'll really get if you divide by 10, which is also easier to do in your head.
I'd look at getting ADSL instead of cable. There have been quite a few problems recently with cable providers being user-unfriendly. Like putting a cap on the amount of bandwidth you can use per month, not telling you what it is, and then cutting you off (or changing your connection to a much slower one) when you exceed it.
Oh, and this is happening next year, so expect things to be different. The cable company will probably be charging more, while DSL will be cheaper. Cable Internet prices haven't really gone anywhere in the past few years, while DSL has been getting cheaper (they used to cost about the same).
David / MRY