Help: Memory novice

[Homewreckers]

I have a new PC and would like to upgrade my memory but I am not sure if i can get any memory.

What I currently have:
HYS64T64000HU-3.7-B
1Rx8 PC2-4200U-444-12-D0
512x2

AMD 64x2 3800 Processor

What I am wondering is what is the 444? Is it MHz?
Can I get PC2-4200 533MHz? Would that cause a problem?

Any other information you can suggest would be great.

 

[computerhakk]

Run your PC through this and it'll tell you what you need and what it supports.

http://www.crucial.com/systemscanner/index.asp

 

[Homewreckers]

WOW! Thanks. That really helped.

 

[elitehacker]

4 4 4 12 is the latency times, its not mhz, PC4200 RAM are just 400Mhz DDR2 RAM, they run with a frequency of 200Mhz, but its effective clock frequency is 400Mhz.