Add a new count column

Let's say we have this:

Country         Capital
-------------    -----------------
USA              Washington D.C.
Ireland          Dublin
Spain            Madrid

How do we write a query without using a #temp table to do this:

ID                 Country         Capital
--------          -------------    -----------------
1                  USA              Washington D.C.
2                  Ireland          Dublin
3                  Spain            Madrid

The ID column should be a new column that's made on the fly, there isn't an ID column in any of my tables. Each row in the ID column should increment by one.

Thanks in advance!

-Chris