Helping people with computers... one answer at a time.
Well, first, let's be clear: there is no version of SP2. It's either there, or it's not.
There are several ways to find out, and find out what other patches post SP2 have been installed as well.
We'll start with the simple: right click on My Computer, select Properties and right there on the General tab you'll see something like this:
Note that it clearly shows Service Pack 2.
If you want to know what post-SP2 updates have also been installed, you can check Add or Remove Programs in Control Panel. That will often list specific additional patches that have been applied since SP2 was installed.
And finally, you can grab any of several utility programs, such as System Information for Windows that will display the very detailed list of all patches applied to your system, whether or not they are represented in Add/Remove programs. Here's an example:
Note that it lists additional KB numbers, which are references to KnowledgeBase articles at Microsoft's support site, as being part of SP3 - which does not exist yet. That's simply its way of listing post-SP2 patches.