Question : Problem: Faster memory available at higher price - worth the difference?

Want to upgrade my memory on my XPS 1330 to 4GB from 2gb (Vista)

Two difference types of memory available from Crucial:

1) DDR2 PC2-6400 " CL=5 " Unbuffered " NON-ECC " DDR2-800 " 1.8V " 256Meg x 64
or
2) DDR2 PC2-5300 " CL=5 " Unbuffered " NON-ECC " DDR2-667 " 1.8V " 256Meg x 64

Option 1) is about 30% more which seems quite a bit. I believe the laptop came with the memory in 2) (but only2GB.
Am I really going to notice the speed difference and does the laptop even support it ( I know it will work but does it actually able to use the increased speed).

Thanks

Answer : Problem: Faster memory available at higher price - worth the difference?

Well, you asked three questions, so let's look at each one:

" ... Faster memory available at higher price - worth the difference? " =>  Only you can decide this one.    We all make those tradeoffs when we decide whether to buy a faster CPU; faster memory; faster hard drive; faster video card; etc.    The performance differences are often nominal ... but sometimes we just want the best :-)

"... Am I really going to notice the speed difference ..." ==> Assuming for the moment that your CPU supports the higher speed memory, the answer is MAYBE.   It depends on whether your typical applications of the laptop are disk-speed limited, CPU-limited, or memory-intensive.   In the latter case, you'd most likely notice that things were a bit quicker;  in the two former cases you'd be unlikely to notice the difference.   But the difference is VERY measureable ... the bandwidth of DDR800 memory is 20% higher than DDR667 memory => and 20% is a rather nice gain.

"... and does the laptop even support it ..." ==> The answer to this question is YES.   But it's the wrong question.   The Dell specifications clearly show that it supports both 667MHz and 800MHz bus frequencies.   The right question is "Will my CPU be able to use DDR800 at its rated speed?" => and that depends on what CPU you have in the system.   What CPU do you have in the laptop?