Question about Graphics Card and PSU

hey guys i was thinking about upgrading my current rig, i already decided to upgrade my CPU to AMD Phenom II X4 955 95W on my M56S-S3 mobo, while still deciding on Graphics Card between HD 6870 and HD 6850

my current PSU is Cooler Master 460 RS-460-PCAR-A3 http://www.coolermaster.com/product.php?product_id=3686

i have question about the power supplies, i think my PSU is 460 watts, but some review says it can only handle up to 430 watts, im not sure the closest review i can find is this
http://www.hardwaresecrets.com/article/Cooler-Master-El...

i wonder whether or not i will be fine with the PowerColor HD 6850 PCS card while keeping my current PSU
the Powercolor power consumption actually cost a little more power than the normal HIS 6850

heres the link to both cards, there's comparison in the bottom
http://techpowerup.com/reviews/Powercolor/HD_6850_PCS_P...
http://techpowerup.com/reviews/HIS/Radeon_HD_6850/

i don't think my psu can actually handle the 6870 and not sure about the Powercolor 6850, it might be too close to the peak, what's the worst that can happen if i use the AMD Phenom II X4 955 95W + PowerColor HD 6850 PCS+ 1 GB while keeping my current psu????

also i live in australia and can pick those parts up for $373 AU in total in MSY
http://www.msy.com.au/Parts/PARTS.pdf should i go on and buy it???
im probably not gonna upgrade any parts again in the next few years after this

and if im gonna get a new psu i might as well do it now
however a normal psu on MSY costs about $100, and if i upgrade the psu i might as well get better cards like the 6870 or better which costs about $50 and more

so for about $150 more i will be getting a new psu and card
is it really worth it????
how much more performance can it bring????

so what do you guys think
can my psu handle the PowerColor HD 6850 PCS???
should i go with that or buy a new psu and new get better cards like 6870???
please leave reply thx