I'm upgrading most of the components in my pc but im wondering if my current power supply (Antec Earthwatts 430) would work fine. Heres my new system specs. My current PSU has two 12V rails with a combined max load of 30A.

MSI 790GX-G65

Sapphire Vapor-X Radeon HD 4870

AMD Phenom X2 550

Crucial Ballistix 4GB ddr3 1333

Possibly? I think if you REALLY want to be safe, you wait a bit longer than what you expected to and buy a PSU as well. You could probably get a 600 and higher watt PSU for around 80-110 bucks with a 12V rail of 40 or more. But you could always take a chance with your current one. Is it really 30A or are you just adding the 12V rails? I was thinking about this myself a while back, and I read up that simply adding isn't the correct way. Hopefully someone that knows more about rails and PSUs can come in. But again, you should just get a new, more powerful one. That way you won't have to worry about it either.

it says on the box that it has a combined max of 30A. The two rails themselves each have a 17A rating. I've had the power supply for around 2 years so im not sure if that makes a difference.

Probably really borderline.  Do you have the required 2 PCI-e power connectors?  The 450W or less PSUs I know of only have 1.
 
edit : looked it up on newegg, your PSU only has 1 6-bin PCI-e power connector, which isn't enough.  I hear you can get a cable to use 2 SATA power for 1 6-bin PCI-e, but I'm not sure how reliable that is.

thats the other thing i was wondering. My power supply has one. but the card comes with two 4pin connectors that convert to the pci-e ones. iv never bought a card that needed the extra connectors so im not sure about that.

If i were you i would def buy a new PSU with the other upgrades.  I don't think your current one will cut it and if it does itll be borderline like the above poster said which can lead to problems.  Here's a link to 3 different systems.  Hopefully it helps you pick a power supply.
 http://www.maximumpc.com/article/features/dream_machine