Ram upgrade for my laptop

[drake]

Hi everyone, new here.

I just bought a compaq presario m2105us that has AMD Mobile Sempron 2800, with a clock speed of 1.6 ghz and 256 mb of ram.

I noticed that my computer is a bit on the slow side, even though I just bought it, reduced the amount of applications running in the background, and adjusted the power settings to make sure that the laptop is making full use of its resources. With this in mind, I have a few questions:

1) Is my AMD mobile sempron processor a, decently speaking, a good processor and could this be contributing to the slowness of the laptop?

2) Since it is slow, and I decided to upgrade my ram, is it better to upgrade it to another 256 mb or 512 mb of ram (it only has one more slot open)? I do not intend on playing games on it, but I do plan on running 2 or more applications in the background, such as browsing on the internet and working with Office at the same time, and listening to music or watch a DVD.

3) Which memory manufacturer should I buy from? Are Corsair, Crucial, and Inifineon good brands?

Thanks a bunch everyone.

[icecube]