Short answer: No
Long answer: The computer you use is just a tool. To be taken seriously you need to have an impressive portfolio of projects, you will be judged by your results and not by the tools you used.
Long answer: The computer you use is just a tool. To be taken seriously you need to have an impressive portfolio of projects, you will be judged by your results and not by the tools you used.
Do as much as you can with whatever computer you have and a copy of gedit or something similar. If you hit the limits of this within the first few months, it's probably your limit, not the tools. If not, then by that time you will be able to determine for yourself what tools you need.
Don't forget the reason why Mac Development is so vogue right now really does have to do with the fact that the OS is based on BSD now, and thus it's a lot easier to get things from the wider Linux world onto the Mac platform. The Linux platform has really been exploding lately, and that's helped Mac out tremendously (In my opinion; Please let me know if I'm talking out of my ass here).
However, don't just go get a Linux box either.
Find what works for you, and go with it.