Thank you very much Nubius for your reply.
Few minutes ago, I called kingston again. The guy there told me this Ram may not compatable with my laptop because they did not test it. And, once again, the guy suggested that I should buy the other kingston Ram that is said "special design" for Dell.... I am so confused.
The model number is KTD-INSP6000A/1G, which number means Kingston technology for Dell inspiron something.
Do you know why? Kingston wanna make more money!!!
And why the kingston have both value ram and special ram? they want to confused us!!!