1) You cannot install two versions of Outlook
2) Uninstalling or upgrading of Outlook doesnt remove data - it all remains
intact - usually the Outlook upgrade proceeds seemlesly & opens with your
existing data, if for some obscure reason it doesnt its a simple matter to
reconnect the old data
3) Whilst the interface of the Office 2007 programs can provide a learning
curve for some, if you are moving from a version of Office for which support
is going to be withdrawn you'll have to get used to it at some stage.
4) Office 2007 can both read data form previous versions & save data in the
old format
5) finally if you upgrade, then decide 2007 is not for you, simply uninstall
it and reinstall your favourite version