Yet another Memorty Stick question

Hi, i just registered, in other words im a noob, and im planning on buying the PSP, why else would i be here. Anyway im also planning to buy a memory stick. So as i search around the forums and found that SanDisk seems to be the popular one amongs everyone. However, people mention buying the Pro Duo model, is this the only model that works with the PSP?

Can you use a regular SanDisk SD stick? if so, is it better/worse? Can you also use the Ultra II models? also is it better or worse than the Pro Duo? Whats the difference between all of them?(i dont know much about memory sticks, i have yet to get a digital camera, pda, or anything that remotely uses memory sticks)

Thank you for your time, i really appreciate it.

You can only use Pro Duo memory sticks.

That's not true, you can use ANY Memory Stick Duo - that can be normal (sticks less than 256MB are usually normal), Pro (usually 256MB or larger), Ultra, etc.

What you CAN'T use is a normal Memory Stick as they are too thick and too long.

Sorry about that, I was just comparing it to the SD MS' since those do not fit in PSPs.