A memory upgrade is typically the easiest and least expensive way to boost your computer's performance. While any time is good to add more memory, there are some scenarios in which adding a memory upgrade makes great sense and can dramatically improve your computer's performance:

You've upgraded your operating system (OS). You've installed memory-intensive software like photo-editing or a 3-D video game.
You work with large files or with three or more programmes at a time. You've added hardware, such as a new processor or a video card. You've purchased a new computer that came with too little system memory.

Laptop DDR2 PC4200 256MB 533MHz Memory Module

Description : 256MB 533MHz DDR2 Non-ECC CL4 SODIMM

Detailed Specifications : Standard 32M X 64 Non-ECC 533MHz 200-pin Unbuffered SODIMM (SDRAM-DDR2, 1.8V, CL4)

The components on this module include eight 32M x 8-bit (8M x 8-bit x 4 Bank) DDR2-533 SDRAM in FBGA packages. This 200-pin SODIMM uses gold contact fingers and requires +1.8V. The electrical and mechanical specifications are as follows :

Features :
Clock Cycle Time (tCK) CL=4 : 3.75ns (min.) / 8ns (max.)

Row Cycle Time (tRC) : 55ns (min.)

Refresh to active/refresh command time (tRFC) : 75ns (min.)

Row Active Time (tRAS) : 40ns (min.) / 70,000ns (max.)

Single Power Supply of : +1.8V (+/- .1V)

Power (IDD0) : 1.440 W (operating)

Operating Temperature : 0o C to 70 C

Storage Temperature : -55o C to +150 C

UL Rating : 94 V - 0