So, you'd think I'd know, but I don't actually read 99.9% of the news items I post. So...what's the difference between these two things:

256MB PC2700 DDR333 SDRAM
256MB PC2100 DDR SDRAM

I've read a bunch of tech specs, but they don't make sense to me (my brain doesn't work that way). Does anybody have a "stupid person" version, like one of them is faster than the other or something?

256MB PC2700 DDR333 SDRAM is faster clocking, your ram needs to match what the motherboard wants PC2100 is the older SDRAM.

Both are older, the newer Motherboards can use PC4400 (DDR 550)

XMS4400 memory is intended for use on ultra-overclockable motherboards based on the Intel 875P "Canterwood" chipset. This memory kit consists of two ultra-high-speed memory modules that have been tested together at DDR550 (275 MHz) on a Canterwood based dual-channel motherboard. Relaxed latency settings allow this module to achieve extraordinarily high clock speeds for optimum performance in extreme overclocking rigs. TwinX matched memory pairs are specifically designed to provide the ultimate in performance and stability in motherboards using chipsets with dual memory channels.

I'm not sure what the last paragraph says, exactly...but thanks for the first part!

The memory and the hard drive size are the only difference between two laptops which have the exact same price...but the better one (60 gig HDD and PC2700) is out of stock while the other one (40 gig HDD and PC2100) is in stock. I don't get to pick the motherboard, and I shan't be overclocking.

Thanks again, I knew someone would know!

The last paragraph refers to one of the fastest desktop memories,( what the future is coming to). as a example of how slow the PC2100 or PC2700 is in comparison.

Ah, gotcha. Well...I'm not too fussed about what's coming, but it's info I'll file away in the back of my brain for future desktop upgrades.

Thanks!