I am planning on getting Windows for my iMac, and I wasnt sure what version/type of windows is should get.
Im dont know whether to get an upgrade, the OEM Version, or anything else.
Welcome to the Apple Support Communities
You are using OS X 10.8.3, so you can install Windows 7 and, depending on the Mac you have, Windows 8. You can check it in this page > http://support.apple.com/kb/HT5634
You shouldn't use a OEM version because you will break the EULA and you won't get support from Microsoft, as it's a version designed to be preinstalled in PCs. You have to get the retail version. Apart from that, if you haven't got Windows installed yet, you have to get the full edition instead of an upgrade edition
Forget about support from MS. They don't support the retail versions.
If it is a System Builder OEM version YES you can use that. What you can't use is an OEM version from a major manufacturer like Dell, HP, Toshiba and the like. Those OEM versions will only install on the manufacturers computers.
As to the other side of support you will not be restricted from downloading any and all of the Windows Updates now available or in the future until MS stops supporting Windows 7. Which won't be for years, like 2020.
You can also currently purchase Parallels 8 at a discount of $49.99 in the March 2013 MacUpdate 10 App Bundle.
Parallels can access the Bootcamp partition if and when you need concurrent access to Windows and Mt. Lion.
Parallels can also install and run Windows XP, but it will be saved into a separate .pvm file for Parallels use -- Mt. Lion cannot have a Windows XP Bootcamp partition, unless your iMac was originally able to boot Snow Leopard or earlier.
Depending on how much RAM you have installed in your iMac and the type of Windows programs you plan on running, like standard Office programs not Graphic intense program like games and photo editing programs, you might be better off using a Virtual Machine software program so you can run both Windows and OS X at the same time. It sure beat having a Dual Boot system, IMHO. Of course that is just the way I feel about Dual Boot systems. You always seem to need to go back to the other OS then back again into the other, Booting and rebooting.
I've been using VMs on both Mac and Windows now for some time and will never have another Dual Boot system.
I need windows becuase theyre are many windows programs that i need for school work and other needs
I want to use bootcamp as i know the OS X and Win will run smoother
You have to buy a SYSTEM BUILDER OEM version. You buy those versions from places like Newegg.com and even Amazon.
DO NOT buy one off eBay that is listed as being a Dell or HP or any other major manufacturer of Windows PCs Branded version. Those versions Will NOT Work. They are only for that Brand of computer.