csrss.exe is required
normally its just sitting there in my taskManager, two instances of it.
One seems to click 1% cpu off and on.
Both insances show about 1,200k memory.. low compared to many other things.
I do use Security Essentials on Vista 32bit

Here is a link that might be useful: http://en.wikipedia.org/wiki/Client/Server_Runtime_Subsystem

did you use the AVG removal tool to fully rid the pc of AVG before installing MSE? If not you definitely need to do so. Here is a link to Corrine's blog with the various tools including AVG
Antivirus Product Removal Tools

definitely csrss.exe is an essential part of your OS and it is set up so that you can not end task on it, if you would it would quickly give you a blue screen/BSOD
you may not have noticed it before but I can assure you it has been there. Be very careful about trying to end tasks on processes you are not familiar with, use a process library/list to look them up before trying to end task on them.
Here is the result at pc pitstop process library for it.
csrss.exe

Many viruses can use the name or similar name to legit processes but the location of where the file is residing is usually the key to if it is the legit file or an impostor.

Not to be alarmed but additional information:

Name: avast! servers

Filename: csrss.exe

Command: C:\Windows\System32\Microsoft\Update\msn\csrss.exe

Description: Added by the Troj/Banker-CLW Internet banking Trojan. If you have this infection you should immediately change all of your online banking account information.

****This infection should not be confused with the legitimate Windows file C:\Windows\System32\csrss.exe.

File Location: %System%

Startup Type: This startup entry is started automatically from a Run, RunOnce, RunServices, or RunServicesOnce entry in the registry.

HijackThis Category: O4 Entry

Note: %System% is a variable that refers to the Windows System folder. By default this is C:\Windows\System for Windows 95/98/ME, C:\Winnt\System32 for Windows NT/2000, or C:\Windows\System32 for Windows XP and Vista.

Source here:
http://www.bleepingcomputer.com/startups/csrss.exe-15230.html

*So as raven pointed out it all depends where csrss.exe is running from! You're probably fine, but get it checked out!

Yes, I removed the AVG removal tool before I added the security essentials. Nothing suspicious has been occurring, although a little longer time is taken when accessing some web pages, inclluding GW sites. I ran MWB again today and it found nothing. Thank you for your responses. Thankfully I could not remove it when I tried.