Hi Flyby, I did this recently and had no problems. There are a number of "advice" sites with details of what to do. Since I am at work, I haven't got the actual references I used, but here is a similar site:
http://www.regstevens.co.uk/add1.htm
Whatever you do, make sure that you have a good floppy "Start-up" disk! Also, do take anti-static precautions when you are doing the actual physical "swap".
Good luck!
