Parallels is a fine piece of software if you need simple virtualization. I've never used v. 9 on an iMac but v. 8 runs like a charm on my MacBook Pro. What are you looking to do with a VM?
You need a copy of Windows to use Parallels so if you don't have a copy, you'll need to get one. You can however try something like Wine (see here) - there's no guarantees that this will work but it's free so it's worth a try.
Won't run via Parallels or BootCamp without a Windows install disc complete with activation code. If as you say 'you have a lot of Windows applications' suggest lashing out on Windows 7 and if your iMac is 64bit, the same in Windows 7.
Using v9 on my iMac (10.9.1) with Windows 8.1 and have previously used Windows 7 both of which run very well. If you can't find alternative Mac software and need to run Windows programs I think you'll find this is very good. As previously noted you will need a full copy of Windows as well as Parallels.
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