What in particular confuses you about Google Keyword tool? There are probably some good hubs here on how to use it. Were it me, I would try to become proficient with the free tool before shelling out for another tool that does more or less the same thing. All the paid keyword tools use Google's keyword data, so why not go directly to the source, which also happens to be totally free?
Another note: You should take positive reviews of the paid keyword tools with a grain of salt. Most have some kind of affiliate program and people will write glowing reviews just to get you to buy it from their links. I've never used Jaaxy, but before you buy it you should find out what it does that Google's free tool does not do.
From the site, it looks like it helps you come up with domain names for niche sites, which the keyword tool doesn't do. But with Google's recent crackdown on exact domain name matches, that's not a very useful service anymore. Plus, if you're not looking to buy a domain name, that feature doesn't help you at all.