I would actually be curious to know what version most customers are using. 2000 is now 4 releases behind the current, and soon to be 5.
Although I think Office 2000 should technically work, it was also the first release with a built-in webDAV client, there might be some additional configuration to get it to work. maybe some digging on the microsoft support site regarding webdav and Office 2000. But, I also think it's a question of support b/w Office and WebDAV; not Office and PLM4P.
Instead, I would recommend using a newer release of Office to avoid this issue, altogether.