In your case I think waiting and saving up for good hardware is the best choice.

Be aware the demo has missing files and although the full version may be somewhat smoother than the demo, more memory is not going to fix what you were experiencing.

FSX is going to be a DX10 flagship product. You will want DX10 when it arrives in March-May 07 because FSX performance a visuals will increase dramatically with DX10. The only downfall is you must install Vista to have DX10 as well which will not be cheap.

My advice is to wait. Unless you just have to have it and cant wait, purchasing todays top end hardware would be the best solution for FSX future-proofing but there will be shifts in the hardware market after xmas which I intend to wait for myself before purchasing anything.

At last everyone has to decide by himself.Wether he should upgrade his Computer or buy a new one.
Btw. this makes me thinking of a marketing idea.The SimV Computer!Designed to play FSX!In Germany some bigger Store Companies(like Aldi) have already a Computer in their stock which was designed to proove good performance for a low price.Maybe we should do the same? But as you can read above,some Hardware is not available yet.So,lets just wait...and see!

I'm running an AMD 3400 + Athalon 64 with XP SP2, 2 GB RAM and a Radeon X1900 and the game runs smooth until things get a bit cluttered then it stutters and the scenery takes a hit, flickering and whatnot... How do you check your frame rates?  I have max frame rates set... but I couldnt tell you what its actually pushing out...

(edit)  I just wanted to chime in on the hardware debate...  Does it really make sense to spend $1000-$2000 to upgrade just to play a $60 game?  It depends on who you ask...  I have a lot of games here that would benefit from an upgrade, so I was planning to build my own dedicated gaming computer to be used only for games... I was going for the low price range of the high end hardware to keep cost down... Planning on Dual core, dual channel, dual vid card... SLI Raid0 Striped HDs... plenty of fans to keep everything nice and cool... no neon lighting...  its too distracting!  The price for this dedicated gaming system is looking at about $1500...  I havent decided yet if it would be worth it...  It would be nice, but do I NEED it?  For someone who is a hardcore gamer, and has plenty of money to throw away, I would say the answer is yes.  To someone who struggled to even buy his last computer that was obsolete before he got it off the shelf, I would probably have to say no.  Me?  I fall blissfully somewhere in the middle...  I have a modicum of disposable income, but I still struggle with the question, is it worth it?

Wayne