Hi Ken,
Just about any current model laptop is going to be be fast enough for decent ReefMaster performance. The best upgrade is going to be memory - and as much as you can justify. Something like 6 - 12GB should do it, and make sure to run 64 bit Windows which can take advantage of all this memory, as 32 bit windows limits each application to something under 4GB of usage. Depending on the map sizes you create, you probably won't need any more than that but its nice to have it when you do - map generating is a very memory intensive process.
Matt