i want to buy a processor ...which are th3 best processor for intel socket LGA 775...and price should be less & performance highest..pl list it ...

You could try the Intel C2Q  which sells for $239.99!
specifics are:
Build or upgrade your performance computer right with the Intel Core 2 Quad Q9550 Processor BX80569Q9550 - 2.83GHz, 12MB Cache, 1333MHz FSB, Yorkfield, Quad-Core, Retail, Socket 775, Processor with Fan. This chip provides an excellent blend of performance and functionality for today’s computers. The quad core performance offers better multitasking and multimedia so that you can spend more time using your computer instead of waiting on it. With support for many of the latest technologies and backed by Intel’s trusted household name, there is no better way to bring your system to life.

• Efficient operation and excellent performance for business or games while using only 95W of power
• State of the art technology conserves power while offering the latest enhancements to get more done
• Excellent compatibility with a wide range of Intel based motherboards and computers
• Included fan provides just the right cooling to get you started quicker and easier
• 12MB cache helps to maximize execution speed and effectiveness

Get the performance you want without sacrificing your hard-earned money with the Intel Core 2 Quad Q9550 Processor BX80569Q9550.

There is also the 3GHz Core 2 duo that sells for $189.99!
specifics are:
The Intel Core 2 Duo processors are built in several of the world's most advanced, high-volume output manufacturing facilities using Intel's leading silicon process technology. The processor family is based on the revolutionary Intel Core microarchitecture, designed to provide powerful yet energy-efficient performance. With the power of dual cores, or computing engines, the processors can manage numerous tasks faster. They also can operate more smoothly when multiple applications are running, such as writing e-mails while downloading music or videos and conducting a virus scan.

• Deliver breakthrough performance and great power savings
• Features 3 GHz processor frequency
• Offers a bus speed of 1333 MHz and 6 MB L2 cache
• Intel Virtualization Technology provides a foundation for widely-deployed virtualization solutions and enables robust hardware assisted virtualization solutions
• Execute Disable Bit allows the processor to classify areas in memory by where application code can execute and where it cannot