Since you don't use Internet Explorer 7 at all, and you only use Mozilla Firefox(current version is 37.0.2), it's not mandatory that you upgrade it to version 9.
Windows Vista doesn't support version 11 like Windows 7 does, so it still would be out-of-date with version 9.
Yeah I figured as much but I was told that certain programs need an up to date IE (per OS) to work. Take a look at this thread here
https://community.mcafee.com/message/376017#376017
I was having troubles with my McAfee and was told that I need an up to date IE for it to work properly.
Have you upgraded it to Service Pack 1 and Service Pack 2?
Yes. I did that years ago.
Have you installed the important/recommended updates that are released every month?
See here's a problem. A few months ago everytime I would update my computer, when it rebooted it never installed Step 3 and my desktop looked different. A window popped up that said "Failed to connect to a Microsoft Service". I had to restore my computer and then reset the winsock netsh. I decided to hide all IE7 updates and I had no problems. Every Vista security update went through fine.
However the other day though when it went to install some security updates, the same problem occurred.
The updates were
Security Update for Windows Vista (KB3046306)
Security Update for Windows Vista (KB3045999)
Security Update for Windows Vista (KB3045685)
Security Update for Windows Vista (KB3046482)
Security Update for Microsoft .NET Framework 2.0 SP2 on Windows Vista SP2 and Windows Server 2008 SP2 x86 (KB3037573)
I had to restore my computer and hide those because I was getting the same problem with the IE7 updates. This was the first time a Vista security update messed up my system.