Is IM Scanning Necessary?

I am currently trialing AVG Internet Security 7.5 and have discovered that it does not scan Windows Live Messenger messages like some other suites. Is this a serious omission or does the resident shield protect me from a virus sent by instant messaging?

 

When (and if) you save any files to your disk, AVG will scan them then.

 

Almost all those extra scanners(email, http, IM, P2P) have always looked dubious in their utility to me. All files have to be written to the computer before being executed, even malicious code imbeded in a web page, and will thus be scanned by the classic AV shield(who usually scan memory process too anyway). As such I really have never grasped the utility of the extra scanners, beside marketing and giving work to the support team that is.

 

IM scanner is good when someone who isn't computer savvy is chatting, there are lots of nasties and can be transferred through a seemingly innocent act of file transfer between friends, would rather see it detected right there and then instead of coming into the hard drive.