PC as chartplotter?
There are many such programs...two low priced versions are NavPak and Figawi. Others include The Capn, and Nobeltec. They all have different capabilities and may read different chart types but all provide GPS input and real time plotting. You''ll want to look at each to see what fits your needs. Look at what chart types they use as well. You can download free charts in the new ENC format from NOAA. They look different than the paper charts you are used to, but they are free. If you want to use them, make sure the software you get supports that format.