Any experience you can get in using computers is likely to help you become a theoretical biologist. Finally, don't forget that computers are used for communicating with people. Try to get on electronic mail or bulletin boards, and locate your peers who are also interested in theoretical biology. They'll be your colleagues and collaborators later. The short answer is yes, because as a theoretical biologist you will often find that the measurements or observations you need simply haven't been done.
Collaborations sometimes work, and often last for years.
But you can only understand the reliability and richness of data by getting some yourself. Thus training as an experimentalist is very important for theoretical biologists. The best training is in someone's lab, going beyond what you get out of laboratory courses. Theoretical biologists are somewhat like square pegs in round holes. Being a part-time experimentalist reduces this necessary tension, which will last so long as vast areas of biology remain near virgin territories for theoretical understanding.