Hi anon. You should take a look at cacharbe's node 153486 which I've used to good effect to get a quick handle on Excel munging.

In particular it contains the following re avoiding Excel's warning dialogs:-

"For the sake of this program, we'll turn off all those pesky alert boxes, such as the SaveAs response "This file already exists", etc. using the DisplayAlerts property.

 
$Excel->{DisplayAlerts}=0;"
[download]

Cheers

hagen