Well I'm running OpenOffice, and it seems fine.
I have taken MS Office XP Pro off my PC, that way I think it will get a better test on my part. It's nice having the Spreadsheets opening in their own windows. With MS Office XP, I found if you have one spreadsheet open, then opened another, it took ages to load. Plus if you then closed that spreadsheet it closed the previous one also. >
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OK MS being ballpark 100MB bigger than OO, means it has more bells and whistle's, but so far it forfills my requirements. Real test is, would I pay £116 + for MS Office Standard, as against the FREE OpenOffice suite, sa far nope