Clint, I just put the two kill commands that you had above into a batch file, ran it and it killed both processes. Now the first time both stopped and then MsMpEng.exe restarted. I manually killed it after that. Then I re-started it and ran my kill.bat again. This time both stopped. So I'm not sure what allowed it to restart itself, but obviously it has some self-protection thing somewhere.
Secondly, I don't think Steve was trying to be a pain with his first response, but as a moderator, I think he believes he needs to warn others who may be attempting things that they shouldn't. Anyway, I hate to see it when posts get nasty. I hope the above helps you.
C:\WINDOWS\system32\taskkill.exe /f /im MsMpEng.exe
C:\WINDOWS\system32\taskkill.exe /f /im msseces.exe
BTW, I also restarted it again, but will probably re-boot. Also, there are programs that I will manually stop for similar reasons to Clint. I can't add anymore memory and it saves me enough to get through the day without getting the running out of virtual memory error and things do run smoother. I wouldn't suggest this for the uninitiated. :O)