So you want to upgrade to MDT 2010 Update 1?
Please be aware of that the rule processing has changed a bit, meaning you may need to add rules for wizard panes you did not have to in the RTM version of MDT 2010.
As a good example, my good friend Mikael Nystrom (fellow MVP) just called on his way back from a customer, where he had to troubleshoot (and fix) an upgrade they tried.The error they got after upgrade was the infamous "Error: 500 = Variable is undefined" message. After adding the /debugcapture switch Mikael figured out it was a variable missing.
In this case the SkipPackageDisplay=YES was missing in customsettings.ini. The customer didn't have any packages, but in MDT 2010 Update 1 they still needed to set the variable to skip the pane.
If you plan to upgrade to MDT 2010 Update 1, do the following,
1. Make a copy of your deployment share (if possible to a lab server)
2. Install MDT 2010 Update 1
3. Upgrade the deployment share
5. If test is succesful, repeat step 1,3 and 4 for the other deployment shares