Straight up question – no matter if you are on SBS 2008 or not, if you are not yet running Service Pack 2 on your Windows Server 2008 installation you should get moving and upgrade to it.
Why? Because it fixes so many issues that affect other third party products and the stability of your server. Take the biggest example is the TDI Driver fix here. Without this fix, your SBS 2008 server that has AV installed such as Trend Micro WFBS 6.0 or other AV solutions, will randomly “lock up” every 7 days or so due to a bug in the Microsoft TDI driver. I’ve heard Microsoft blame Trend for this, and then later Trend blame Microsoft – end result is our clients being caught in the middle.
Long story short – upgrade your Windows Server 2008 to Service Pack 2 ASAP to avoid the issues.
I believe that vendors such as Trend Micro who can be greatly affected by NOT having things such as Service Pack 2 installed, should make this SP a mandatory item for their product installations.