I have been damn impressed with my Macintosh iBook. I have Dreamweaver, Flash, Illustrator, and Fireworks. I can also use GNU programs like the gimp and gaim. I dare not speak of Word or Excel, but Mariner Write is one of the coolest word processors I have ever used, and it only costs like $60. Total number of crashes in the last 18 months - 2. Total number of required restarts - like 15. Total number of antivirus programs - 0.
If you want to hold onto your design tools, I suggest a Mac. Sure, you can get the programs running in Linux, but it's somewhat buggy and slow. And, to be perfectly honest, you probably don't want to learn a whole new computing paradigm at this point in your life. Macs are high value for the money, and OSX is an incredible OS.
If you DO want to learn a new and challenging but exciting way of computing, I and others would be more than happy to help you get started with Linux.