Here is some interesting keyword info I got from Jim Morris (NicheBot).
WordTracker = 0.63% of all Internet traffic (coming from Dogpile and Metacrawler) and is valid for the last 100 days.
Keyword Discovery = 1% of all Internet traffic (coming from a toolbar used on browswers in making searches) and is valid for the last year. There are 2 databases: (1) Premium, which is the current one (about a billion search terms), and (2) Historical, which has about 32 billion search terms but the figures are all over the map. The Historical Database is used mostly to suggest long-tail phrases.
Google = +-50% of all Internet traffic (coming only from Google) and is valid for the last year, but Google also omits stuff all the time to keep ahead of gamers.
Just something to think about when doing keyword research. You read right, too. WordTracker and Keyword Discovery together represent less than 2% of Internet searches while Google gets around 50%. This is for traffic.
For number of sites (competition), use the intitle:
http://URL command to get pages actually optimized for the keyword, which is the real competition. Simple number of pages will change, but the optimized ones will tend to stick around. And they will compete on purpose.
If you don't understand what this means or implies, look it up. You might learn something (and it is well worth learning). Even if you don't, put it in your writing, anyway. It's both correct and great BS to impress customers with.