things to consider the mac makes more of its os hidden and unable to be edited with ease
depending on what language u are use to you will need to re learn it since the winapi no longer applys and some languages are not compatible atal with java being a exeption since runs on nearly all os's
mac's usally cost more and altho do handle certain things better i find 90% of software i rely on only works on windows
and altho they do certain things better most games are not realised on them to truely use that power
same with the ide you probs use to program (even if it is java you may find you cant use the ide your comftable with ) netbeans works on all os tho
and not only is it totaly new thing to learn both for navigation around the os but also with call funtions in proggraming its also means half your apps are no longer compatible with your previous customers (if all your previous customers are use to you writen apps for them in windows how do you intend to now start develping it on mac)
but for video editing and open gl i do find them very good and they do look nice
may of been a idear to tell us the languages you use and what you mainly develop
and altho mac boast it can run windows rember it is in a virtual machine its not quite the same also windows can run mac aswell
peronaly i dabble with other os and altho people have a go at windows iv been using it since windows 3.1 when i was about 5, i have done other things such as linux python and c in linux but windows has a familuarity and feel im use to and i dont think its rite to chuck it in for a pc just yet since it serves me so well if i did that means all my old games and software no longer run and the 1s that do are not supported( if it crashes after 4 hours in middle of project and i lose tons of work and cant load it the company that makes it turns around and says oo we dnt offer suport under mac\ linux wine)
which is really important if your a software developer you will proably have paid for some usefull tools to help you a pro ver of ur ide with suport a few addons also editing tools like spy++ to get window handles non of that works no more and if u do get it going on a emulator \ virtual machine it aint suported
and to person below "The recent Macintosh computers have Intel processors, you can run Windows or various Linux distributions on them as well as Macintosh OS X. If you want to program for more than one platform, you can do it on one machine with a Mac." that is a = since window can also run mac http://www.windowsdevcenter.com/pub/a/windows/2005/01/18/PearPC.html
so you can develop every thing for nearly every os on windows aswell (virutal pc and vm ware) :) hardly a usp
edit edit : ok cetain ver of mac you cant Caoimhin B but same and u cant run every ver of linux and windows on mac i was just sayin dont rule out pc since mac boast it can run windows well there proof of windows runing mac :) and same with the unsported side you argue if u call up microsoft tell them direct x model make crashed in middle runing it in a vm on mac they will laughte in ur face and tell u to go away in a stronger tone so nither 1 others suport
-------------------------just rabling now
but my mate got a mac recently and works okish if you want it for what there designed for (music , videos , internet ) same with windows but when u want to get deeper its so much harder i found and you suddenly find oo my mobile phone dont connect no more since it requires its own unique driver which is only avalible on windows same with various other things since they dont use genric drivers and so on
and Caoimhin B has almost conviced me but compling test where faster on mac sorry 200 pages of script compiles in less than a few secounds on windows less time than it takes me to have a sip my drink any way lol i dont see the fact mac does it in less time a major disadvantage and .net is a great tool for both apps and server
but yeh intel and ms are working very hard to make macs more compatible of late but i dnt think .net will go to mac's any time soon other wise what will windows have left maybe a mini version will go but linq and so it fixed with ms for quite a while i feel
EDIT AFTER MORE INFO
I specialize now mostly in Web Development.
PHP, AJAX, JAVASCRIPT, CSS, HTML, FLASH ETC ETC
your a web developer then nearly every thin will be exacly the same and ignore most of my post since i was asuming u did app developing which is totaly diffrent for mac and pc , a mac should not really change the way you do things much