We also use Command and whilst we were running it under Win 98 with 3year old machines there were a lot of tears.
We now have XP / new machines and it's a lot more stable.
Still has a couple of issues that prevent it from being a real Professional package - ask any of our pilots.
They prefer to sit at a machine rather than use the standard plans - maybe so they have somewhere to drink coffee....
The Jepp one is VERY good

- they were trying to get it to interface with NAIPS about 18 months ago, I gave up phoning as they kept saying ' out in a couple of months'
Fizzy