How to find out which Sharepoint Products are being used

[whitesox99]

Hi,

I am very very new to this MS Sharepoint and have a question. How do we find out what Sharepoint products are being used. Actually a client needs to upgrade there Sharepoint to the lates version but don't know what current version and product is being used today. It can be one of the following:

SharePoint Team Services OR
Windows SharePoint Services OR
SharePoint Portal Server 2001 OR
SharePoint Portal Server 2003

Is there an easier way to find out exactly which of the above are being used i.e. what can be the possible links to admin page where it shows the version and product as myself I have never worked on Sharepoint so don't know. As it will help to further drill down on the upgrade path.

Also on what Operating Systems can we install the following Products. Can we install the below products on any windows OS i.e. Win 2k, Win Xp, Win 2003

SharePoint Team Services OR
Windows SharePoint Services OR
SharePoint Portal Server 2001 OR
SharePoint Portal Server 2003

Any help is appreciated.

Thanks