Alt+F4: Give us your machine specs. Linux does not run too well on older machines, but it runs much much more efficiently on modern machines. I use FreeBSD for my older machines simply because of it's architecture simplicity/efficiency that allows for a much smaller kernel for practical use (it is a very refined architecture, but it also has a lot of hyped pumped in). Anyhows, I would always recommend Linux over FreeBSD as a development platforms at FreeBSD's current state.

er0k: I would say both offer identical development environments, the only difference Linux has much more support in general from both commercial and personal entities that allows you to have a lot more development puff (libraries, etc...)