I am thinking about getting a GPS and want to know what the basic features that I need are. I probably want one that has at least topigraphical maps. what else do I need to look for (keep in mind I know nothing about them)

rechargable battery?
DC plug?
waterproof?
.....?

I myself prefer the mapping hand helds Garmin

I also recommend the Garmin mapping handhelds, except for the ones that do not have data card capability.

Waterproof is necessary if used outdoors. Garmin waterproofs are up to 1 meter submerged for 30 minutes.

I think data card is a must have.

I use a mobile power cord and have wired it in permanently so that when the key is on the unit is operating on external power. That extends battery life to several days instead of a few hours.

Topo maps are extra. They are nice to have, but can make the display very busy. Topos are good when exploring, otherwise, I don't use it. Some of the higher end units have one built in for a higher price... the topo is always extra.

Rechargable batteries are a plus, but not an absolute.

If you plan to use it on an ATV, a RAM mount is highly recommended.

If you plan to use it inside a vehicle, an external antenna is a plus.

The best prices are generally found at www.gpscity.com.

I would think a compass would be nice???

Like Dan said the data card is a great asset. I have an older 60c that does not have the data card and it is OK but a I will get me one with a data card one of these days then I will be able to use the maps that Dan has.

Personally I would stay away from the "H" or "HC" Garmin models... these are extremely limited, specifically to internal memory size.