How to get ios 4 apps work on ios 3.1.3 iphone?

I got an iphone 2g, redsn0w jailbroken but its ios 3.1.3, can't be upgraded anymore. Most of the good apps require ios 4.3, any idea how to get them on my phone? Next year i'm getting the 4s or 5:)

You can't. That is impossible. If they need iOS 4.3, then they NEED 4.3. Therefore, it is not possible to run it on your iPhone at all. Even if your iPhone is jailbroken, it still won't work.

You'll have to buy a newer iPhone that can run some of the latest versions of iOS. Getting an iPhone 4S next year would be idiotic.