Hi Kevin,
I use GRLevel3. Level 2 is more for the met experts out there. (You do not need to buy anything for Level 3 data ... it is free and readily available... but Level 2 data will cost you some money unless you can find a free source.)
All I use is GRLevel3 without a subscription to anything.
GrLevel3 is actually pretty easy to use... you have a LOT of options but really, I mostly only use the radar image (I like BR248) and the base velocity images (to see where the tornadic activity is).
There's actually a copy of the FAQ available to the public on
http://www.grlevelxstuff.com/board/index.php?topic=13.0They also have some excellent flash videos on how to do things.
Most stuff is pretty simple though...
Go under site and setup your default radar location.
Download a background from:
http://www.myweatherstations.com/grsmaps.shtml-or-
http://www.allisonhouse.com/grlevelx/maps/How to use background images:
1) Right click on the image you want and do a "Save Target as..." and save file to your computer
2) Extract the .zip file. Inside are two files: a text file and an image file
3) You'll want to put the image file some place safe (may we suggest the GRLevelx folder)
4) Open the text file in a text editor like Notepad. It contains some numbers that you'll need in a minute.
5) With GRLevelX open, go under GIS... Settings... Background
6) This opens another window. Click the ... under Background Bitmap to select the BMP file you downloaded
7) Under Longitude From and To, Latitude From and To, copy the numbers provided from the text file
Hit OK and your background should appear
Go under products and turn on storm attributes and warnings (now your right hand buttons are lit up).
And that's about it... you're ready to play.
It took maybe a day of playing around to learn this and that... having an FAQ does help... and grlevelxstuff.com has become an excellent resource.