How do I know if and what version of .NET Framework I have?

I am running Windows XP Pro 32 bit (sp3) and a program that I am trying to install says that I need x86 .NET Framework 2.0 SP2. How can I find out if and what version I have?
Thank you.

all the versions installed will be listed here, and they should also be listed in the add/remove programs list.
Elizabeth, it's always a pleasure hearing from you. Thank you for your help. I tried copying and pasting, but it wouldn't accept it, so I went to Installed Programs and found Microsoft .NET FRAMEWORK 4.0 Extended already installed. Why do you suppose the program I want to install asks for x86 FRAMEWORK 2.0 (sp2)?

Thank you for your continued support :)

because .net 4 is a standalone .net, the others all cumulative and cannot be installed separately.

copy and paste???

above is the key you look for in regedit, are you familiar with looking in regedit?
Sorry about that. I misunderstood. I am familiar with Regedit. If .net 2 Framework sp2 isn't there, can I install it? It isn't listed in Add/Remove Programs. Where can I download it from? Maybe I'm getting myself into more trouble for just a simple update for a program that is working fine now. Please let me know what you think. :)
Elizabeth, once more you came to the rescue! I temporarily disabled my Anti-Virus program and I followed your link and downloaded and installed .NET FRAMEWORK 2.0 SP2. It then recommended that I install a security patch, which I also did. Everything went perfectly! You are a great asset to the XP forums!

After doing that, I was able to successfully install the program that required FRAMEWORK 2.0

Thank you so much for your help :)