How many more years do you think I have?

I built my pc 2 years ago, and I was just wondering how many years it can go without upgrading to play any upcoming games at playable settings

Specs:
AMD phenom x4 9950 BE quadcore 2.6ghz
6gb ddr2 ram
Nvidia GTX 460 1gb gddr5

Imho around 5-6 years. There are no milestone changes in computer hardware at now. Max temperature at cpu is reached, so they are changeing only firmware and adding more cores (Which game uses wisely more than 2 cores? Not every new game uses 2... lol) what incrasing energy consumption. 128bit cpu can go to pc, but there will be large compatibility problems so...
New version of DX will probably go out for 2 years but DX11 will be in use for around 6 more (pointing at DX9). Maaaybe you will need to add more ram in future but for those years even 6gb should be enought.

Your sytsem is very similar to mine.

AMD Phenom I 9850 Black Edition (2.6 OC'd to 3.1)
4x1GB Kingston HyperX DDR2 800Mhz
Radeon HD 4870 512MB

And I am upgrading at the end of this year...I am giving this computer to my brother or my dad.

Several more years. 4 years sounds about right.

My system is about 8 years old now, and it still runs GW at max settings (as long as AA is turned off).

You've most likely got another 4+ years before you have to upgrade.

I'm running an AMD X2 at 4200 with 3 gigs and an Nvidia 9600GT, plays everything I've thrown at it fine, seeing as how your rig is newer, has mor umph id say about 6-7 years.

Well let's see, your processor is going to be 3 full generations outdated in about 1 month, the video card is 1 generation outdated, and you are running 6 GB in a dual channel system (fyi dual channel requires 2, 4, 8 to work properly).
Any serious gamer will tell you that parts of your system are outdated right now. However, it really depends on what games you play and what resolution you game at. There is a world of difference in playing a game like Crysis 2 @ 1080p with max settings and 8x AA compared to a less graphics intense/ older game at 1024 x 768 with Medium settings.

*basically what I am saying is right now your CPU is a bottleneck, either OC the heck out of it or get a newer one, if your mobo supports it. Your system will perform better if you drop down to 4GB or upgrade to 8GB so that it actually runs in dual channel mode instead of single, and your GPU will handle games for a couple more years if you are content to play at lower resolutions and medium settings depending on which game of course.

I think this is a loaded question since we don't know what newer games will require. The only things that don't need upgrading on a regular basis is the case and the PSU.

Speaking for myself, I have a 1995 Emachine w3400 with stock CPU/Mobo but I did upgrade my video card, ram and PSU. This was around two or three years ago. With this being said, I'm still able to run quite a few MMRPGs (WOW, COX, GW, DDO, CO and LOTR) and RTS (Company of Heroes, Age of Mythology, LOTR, the Dawn of War Quadrilogy and Dawn of War 2)

I am planning on building a new pc in the near future but I need to save up for it

You'll be good until the PS4/Xbox 3 comes out. About 2-3 years?

If it runs GW well it will run GW2 which imo will be around for a long time.

That said, minor upgrades are fairly cheap and will help add time and improve visuals in game.

Me thinks thee had a brain fart. You can have 2x2Gigs + 2x1Gig - that is a 2Gig and a 1Gig in each channel - for a total of 6Gig, dual channel.

The video card is quite good. It will probably bottleneck at medium settings in about two three years at least (although minimum spec will be lower than that). With a bit of overclocking (depending on PSU) and a cheap 3rd party cooler (Hyper 212+), you can squeeze a a bit more out of it.

If you are talking about GW and GW2, it's isn't requiring high spec anyway. But more modern flashy games will be.

hmmm - I think thou art correct, verily, I shall endeavor to refrain this frail shell of a mind from hasty assumptions. (aka not all 6 GB = 3 x 2GB DIMMs)