worth upgrading?

[vexvegaz]

$500 just landed in my bank account

and im thinkin i should just use it for some upgrades
my current specs are in my sig. im really itching for a sli setup(no ati pls)

my thoughts so far

dfi lanparty & a 7900gt (will pick up the second gt sumtime this summer)

thanks in advance for ur opinions guys
v.vegaz