Generating circles

[N R A]

Can anyone help with this problem. I have a list of 'sites' - actually 
ground water abstraction sites - and I want to produce some maps which 
shows a 1 km circle around each one. These maps will act as overlaps for 
some of our personnel - they want to be able to look at a map coordinate 
and check whether the point is close to an abstraction point.

I can load the points as sites, but whats the best way to produce the 
'overlay' - I'd thought of it as being a simple raster layer, with 0/1 
values for inside/outside the 1 km zone. How can I convert a single site 
into a circle of radius 1 km ??

Sorry if this is a really silly question, but I'm a chemist who's learnt 
about computers, not a GIS expert  8-(

Thanks for any help,

Steve Culshaw
NRA North West
e-mail : nra at cix.compulink.co.uk (use this for general usage)
or         sculshaw at cix.compulink.co.uk (Private - only checked at best 
biweekly)