hello guys i need some advice currenlty i am running

Phenom II X4 945 @ 3.00 ghz (stock)
Gigabyte 785g Chipset
4 gb ddr2 800 bus
750 gb hdd
ATI sapphire 4870 512 mb GC (running at ref clocks)
1 DVD writer
Gigabyte Superb 720w PSU

Now everythin is running very smoothly i can game any game at 4xaa/16af high to very high at 1680x1050 even some at 1920x1200
its working very fine running for 2 months now so should i change my psu?
is it a good psu i got? gigabyte website says its 610w true power
i dont plan to OC anything i calculated my psu using antecs and enermax psu calculator it says i need 392 w only with 90% cpu load and 30% capacitor age

i plan to upgrade to

core i5 750/860
normal h55/p55 mATX mobo
4 gb ddr3 1333/1600
750 gb hdd (same)
ati 5850/5870 (or gtx 360/gtx 380)

i calculated again with above specs with 5870 and i7 860 at 90% load and 30% aging it says 377W ??!! hows that possible ? does power consumption of 5870 and i7 860 lower than 4870 and PHII 945 3.00 ghz??

so should i keep my current psu? or upgrade? if i keep it  i plan to keep it for a year running i7 860+5870 is it ok?

also upgrading from phII 945 to i7 860will i get that much difference?
or should  use ph II 945 for a year until 32nm quads arrive?