No, any ISP will work. I've had my DC on the internet with Netzero, Juno, and freeweb before it went down. Just use your login and PW as normal and it should work.
If you want to download save files, remember that there are usually two different types of save files, one for regular VMU's (where you can direct download them to your VMU) and ones that are specially made for the mem. cards that have a PC slot (which would be useless to you).