upgrade time.. advice needed on best route

[G1BB0]

pc spec is...
c2d 4300 @ 2.8ghz (does 3 stable but dont want to kill it)
asus p5ne-sli
4gb ocz reaper 6400 ddr2
ati 4850 512mb
250gb wd sata 7200rpm
corsair hx520w

win 7 ultimate 64bit

monitor is dell 2005fpw 1680x1050

now I know this pc is getting a bit old but tbh it runs all my games comfortably cs:s, cod4 mw, l4d2, tf2, dragon age, race07 etc

my son has an fx57 system with 2x 7900gtx 256mb in sli and I was gonna give him my 4850 and sell the 7900's (I know they aint worth a lot but every £ counts ) it does him for now and if/as/when I do upgrade full pc he will have my current one and my daughter can have his for her sims3 rubbish lol

I want to change my monitor to a 24" but which card will run at 1920x1080 with my current cpu etc or should I just wait and go i5/i7 or am3 in a few months time when funds permit?

budget is approx 200 quid give or take but not really sure what the best way to go would be as dont want to just spend for the sake of it if the end result is not going to benefit much

thanks in advance

 

[antipacker]

get a 5850

 

[antipacker]

or a hd4890 will serve you well and save you £70

 

[G1BB0]

how much will my lowly 4300 bottleneck a 5850, that would be my choice at the mo once they hit £200 again as idx11 capable and also means I can transfer it to new pc when I upgrade.

will a 5850 fit in a thermaltake soprano and is my psu ok for that?

 

[antipacker]

psu should be ok. i had one of those cases years ago quite small.

will get soe measurements for you

 

[G1BB0]

cheers, the 4850 is quite long (got a vortex on and it looks massive but seeing the pics of the new cards... they are huge) I got about an inch spare to the hdd cage

 

[antipacker]

cheers, the 4850 is quite long (got a vortex on and it looks massive but seeing the pics of the new cards... they are huge) I got about an inch spare to the hdd cage

5850 is 9.5" inch long.

 

[G1BB0]

cheers, just measured and got 10.5 inches to drive cage

I am assuming the 5850 will be a good boost, how much would my cpu/mobo/ram restrict its full potential?