I have found an entry for Drv in Add/Remove programs for WinXP-Pro/SP3. What might it be, or how can I find out ?

You have asked the same question in multiple places:

Identifying programs « How-To Geek Forums
Identifying programs in WinXP-Pro/SP3
Identifying programs in WinXP-Pro/SP3
http://grownupgeek.com/identifying-p...s-winxp-prosp3

That is called shotgun posting and generally is not considered good forum etiquette as it ties up limited resources and can result in conflicting advice and confusing results. And I note you have not responded to some.

So I recommend you wait and see how those play out.