Possible To Lock A Row Within A Stored Procedure In SQL Server 2000?

Hi All,

I have a table that holds pregenerated member IDs.

This table is used to assign an available member id to web site
visitors who choose to register with the site

So, conceptually the process has been, from the site (in ASP), to:

- select the top record from the members table where the assigned flag
= 0

- update the row with details about the new member and change the
assigned flag to 1

- return the selected member id to the web page

Now I'm dealing with the idea that there may be brief, high traffic
periods of registration, so I'm trying to build a method (stored
procedure?) that will ensure the same member id isn't returned by the
select statement if more than 1 request to register happens at the
same instant.

So, my question is, is there a way, once a record has been selected,
to exclude that record from other select requests, within the bounds
of a stored procedure?

ie:

- select statement is executed and row is instantly locked; any other
select statement running at that exact moment will receive a different
row returned and sill similarly lock it, ad nauseum for as many
simultaneous select statements as take place
- row is updated with details and flag is updated to indicate the
member id is no longer unassigned
- row is released for general purposes etc

If what I'm suggesting above isn't practical, can anyone help me
identify a different way of achieving the same result?

Any help immensely, immensely appreciated!

Much warmth,

Murray