Is it really important to defrag PC's registry every once in a while? Or Defragging the drive itself is enough?

I'm planning to but a new laptop soon and I'm a bit confused whether I'd choose MACBOOK PRO or SONY VAIO CW series or the F series. And I just want to know whether it's really necessary to defrag the registry on PCs as compared to Macs which I think is not needed anymore and if that's the case then choosing Mac over PC would be my choice for it would make my cyber life more convenient. However, there are other things that I love about PCs as well. When it comes to compatibility and all that stuff I think PC wins versus Mac. Please help me out with this. Thanks a lot! :-)