It is a relevant question. The Athlon at 2.2ghz is faster, but....
The X2 with 2 cores can do more work, and make your PC run much more "smoothly". Simply, while one core is working to run an application or game, the other core can be handling background tasks, and your OS.
If a program that is written to use more than 1 CPU core is being used, the difference in speed the X2 can perform at is greatly enhanced over the single core, even though it is clocked a little higher.
In short, if these 2 CPU's are your choice, the X2 will lend you much better overall performance.