fs9 upgrade for addons

i have and AMD 3000, 1024megs of ram, 9600 ATI video card and a 40 gig HD. i have it set up where i can fly the default aircraft into ANY airport with downloaded weather in stormy conditions and get silky smooth framerates. freeware aircraft run pretty good too but...i want to get some of these payware aircraft i drool over but i want them to run as smooth as the defaults. i assuming i'll need to upgrade again for these so here's my question. what will i need? new MB and video card i guess maybe and CPU. i'm not interested in upgrading for FSX. i'm running at 1024 resolution now but would like to get up to 1600x1200 with alot of 3D clouds and still get an extra smooth flight. oh yea i mainly use the VC when flying also. thanks, william