Hey guys I'm going to purchase a new Desktop.I want to a very powerful computer that can last atleast 3-4 years.Help me find me the specs.

I will most likely be buying an a Dell XPS or Sony VAIO,help me decide the better brand and quality

One more thing,I am thinking of going for the All In One PC's,should i or not?

I am gonna use it for High-Def,Gaming,Blu-ray,Photoshop,some technicle work,etc.Lets just say it should be top notch.

I was also thinking of getting the new Core i7

The budget is about $2000

Neither, you go to www.newegg.com and build yourself one for 75%+ off. If you think it's hard it really isn't, it's like  playing with legos, piees go where they fit and you are done. Use google to see which pieces you want.

Build your own. You'll probably end up spending much less (or about the same for a more powerful system), and all it takes is a few hours' worth of assembly and installation. Oh, and you don't need to deal with pre-installed bloatware.

If you have to choose, your choose should be Dell XP, Dell gives you more for less

None of them. Just buy the parts you want.

No one here's going to tell you anything other than to build it yourself.

Which, isn't a hard thing to do, really.

Just tell us what you're going to be using it for, and we can help you pick out the parts. Putting it together's like playing with Lego, only more expensive, really.

Go DELL, no one here that pointed for a mounted PC knows that DELL PC´s don´t have fan noise... it´s the truth..

I prefer mouting on by myself and getting at least 30% off... but... they stay with fan noise... to balance that before buying.

Build your own. It'll be half the price and much better balanced than the usual "OMG 12GB of RAM" and integrated graphics.

Don't buy an All-in-One, the premium is large compared to normal Dells and astronomic compared to building yourself. Micro-ATX boards are already small enough to be unobtrusive.

Can you tell us what the computer will be used for? Which applications, which games, and for the games what settings and resolutions do you use?

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Assuming general office tasks (nothing too intensive), and gaming on High at 1600x1200 or thereabouts:

CPU: Phenom II X3 720 ($120)
Graphics: Geforce GTS 250 ($110)
OR Radeon HD5750 ($145) if you're willing to pay a bit more for lower power consumption and noise
RAM: 4GB DDR3-1333 (~$80)
Motherboard: 785G (DDR3) ($80)
HDD: 1TB (~$80)
Case and >=450W PSU (~$50)
DVD Burner (~$26)

Total: ~$550 for case hardware

High-end machine for video encoding, photo editing, and gaming on 1920x1200 Max settings:

CPU: Phenom II X4 955 ($169)
Graphics: Radeon HD5850 ($259) Note: hard to find at RRP now, so the choice is wait a few weeks or pay a $50 premium now. There is no serious Nvidia competition to this; it outruns the $360+ GTX285 by 20-30%.
RAM: 4GB DDR3-1333 (~$80)
Motherboard: 785G (DDR3) ($80)
HDD: 1TB (~$80)
Case and >=450W PSU (~$50)
DVD Burner (~$26)

Total: ~$750 for case hardware

Dell also charges several arms and several legs for their computers, especially if you want more than the bare minimum.

I spent a grand in July on my comp, with 4 GB DDR3, a Phenom II 955 and a Radeon HD 4870.

Then I checked at Dell, and to build something with a Phenom II 940, 4 GB DDR2 and a lower Radeon HD 4xxx, it was about two grand, IIRC.

go Dell or built it yourself or go to a popular computer shop where they can assemble the parts for you