This page will take you through some stuff that is not really out there to help folks with GPS information. Information that's not readily available without hands-on experience. I'm just going to cover information about the Lowrance I-Finder Hand Held units and Lowrance fish finders with GPS capability. This really won't take that long to show you a lot of stuff that you just can't read on the Lowrance site and understand. It's probably there but it's confusing, so let's take away some of the confusion now.
First off, when you order your new I-Finder the H20 is probably the best one to get. It's water proof and a good all around unit. Things that don't come with it is the ability to load the downloadable maps off the Lowrance web site. In order to do that you have to have a SD/MMC reader/writer. You can get these with MapCreate package but you can also just buy the reader/writer from RadioShack for $9.00 or so if you don't want to spend a lot of money on map software that you may never use. MapCreate maps are handy though as I've got some for my area loaded on my SD chip and they show ponds and old lease roads that don't come with the Unit. All the old back-roads are on MapCreate and a lot of other things as well. So it's a good thing to have if you have the money to purchase MapCreate.
The maps that are in the unit when it comes from the factory are pretty plain but they show major highways and what not and the lake maps aren't very detailed but if all you want is a unit to show WayPoints that you mark on it so you can return to them at another time. Like if you find some structure out in the middle of the lake you can mark the Waypoint on your GPS and return to that exact spot. This is also handy for trotliners. If you set a trotline you can mark the spot where it is on your GPS and return to that spot with pinpoint accuracy and you don't have to have a marker jug tied to the line. You can use a drag made of lead to drag for your line instead of having a jug tied to it that anyone can see and check your lines for you. But, back to the GPS information. If you just want to mark WayPoints and save them on your GPS and you don't care too much about detailed lake maps like the Enhanced maps you can download at http://www.lowrance.com/Products/Mapping/LakeMaps/index.asp then all you need is an SD chip which doesn't come with the unit. You can purchase a 512 meg SD chip from Wal-Mart for about $14. They're located in the Phone/Camera section in the Electronics Department. That's all you need extra for just marking WayPoints. Now this information may be a little off as you may not need the SD chip but I think you do in order to save WayPoints and other input information.
When you get your Unit they'll probably already have upgrades for it when you get it. I purchased a new Lowrance 334c iGPS and there was a software update for it on their site before I even purchased the unit. I went to RadioShack and purchased the SD/MMC card reader/writer and a new $14 chip from walmart and loaded the software update on it and put the card in my 334 iGPS and it automatically upgrades all by itself when you put the chip in the unit and turn it on. Lowrance product updates are at http://www.lowrance.com/Downloads/Updates/default.asp so in order to use these updates you need the $8 reader/writer from RadioShack. The kind I got was the Dazzle SD/MMC card reader/writer. After looking that up I see the price of them has dropped down quite a bit. They're just $8 now, I paid $20 for mine. It plugs into your USB port on your computer and if you're running WindowsXP you don't need any drivers or anything because XP will automatically see it when you plug it into your USB port and map it as a Drive Letter on your computer, like it's another hard drive or CDRom and all you do is copy the files onto that drive letter when you download them from Lowrance. Simple HuH?! Well it is when someone explains it to ya like I'm doing here.
You can actually get 1 and 2 gig SD chips but they're not necessary ... the 8 or 16 meg chips that Lowrance sells for $50 or however much they are will hold a lot of maps so a 512 meg chip will hold as many maps as you could ever use on your GPS. Now where the big 1 and 2 gig chips may come in handy is where you're going to log your fishfinder output and then read them with Lowrance's Sonar Log Viewer . The handy thing about having the 1 or 2 gig SD cards is you'll be able to log a lot longer than you can on the smaller chips ... I think I can log 5 to 8 hours on my 512 meg chip so if you want to log more hours than that you'll need to spend about $40 on one of the 2 gig chips.
I was at Wal-Mart the other day and the 512 meg chips were $14.97, 1gig at $17+, 2 gig was between $34 and $39 depending on the brand.
That's about all there is to it. If you have any questions be sure to ask them on the forum or you can email me at firstname.lastname@example.org