I would recommend specifying you're excel object version, just for the sake of being very explicit. You can check if its 9 or 10 (probably 10 for XP) in the OLE object browser installed w/ ActivePerl

That aside I use Win32::OLE for the exact things you're talking about, and it runs with zero problem. p4-2.4Ghz 1GB RAM.

Anti-virus software could make a difference, because I know NAV will scan a document as you open it, maybe it's (if you're using NAV) having some issue with you creating that document, but it doesn't sound likely