Don't shoot the messenger and please don't start another FS9/FSX debate.
My simple reason for not upgrading to FSX is I can't be bothered to spend any more money on FS. I could afford it but FS has taken a back seat for the past 6+ months. I've got a very nice Saitek X-52 joystick and pedals that have rarely been out of the box. Plus lots of FS9 add-ons that have been ignored and need more attention.
For some reason I can't get interested in FS right now. It can't be a mid-life crisis since I had that when I was 33. :o
Damn... I bought my FSX off eBay for £26 brand new ... did not think that it could be got cheaper... Anyway I would suggest you go and buy it quick, with the patches it runs very well even on my mediocre machine! Just dont throw away FS9 ...you may regret it ;-)
AMD Phenom II X4 BE 965 @ 3.80GHz
nVidia GTX 560 TI 448 Cores