I picked up an eBay bargain of a proper Fault code reader -- Snap on blue point Datacheck 200 that talks to Rover MEMS.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=7948610552&ssPageName=STRK:MEWN:IT

As my cars are all pre year 2000 I don't need a unit an OBD/EOBD yet but have been keeping an eye on the market --- a lot of iinteresting stuff on the market and the price is falling here are a few of the urls I collected
http://www.espautomotive.com/trolleyed/index.htm
http://www.scantool.net/products/elmscan_vpw.htm
http://www.gendan.co.uk/viewproduct.php?product=STNISO
http://www.obddiagnostics.com/order.html
http://www.digimoto.com/order.htm