I have a quick question. I have tried to change the default file format that Excel uses to save documents to the .xlsx format. I have gone into the Excel Options, clicked Save in the left hand column, and changed the "Save files in this format" field to show xlsx. Then I click OK. However, the next time I open Excel, the default file format has gone back to .xls. I can't get it to keep the new setting once the program is closed. Is there something else that I need to do to make this stick?

looks like you need to do it through Group Policy Console -

http://technet.microsoft.com/en-us/library/cc179057%28office.12%29.aspx

i couldn't find it on my comp at work, so assume will need to contact admin person..
l