Gaming Newb question: Upgrading Laptop ram

[RupeeClock]

Alright, I have some questions about Laptop ram.
I've done ram upgrades for PCs before, dead easy, but I've never done laptops so I have a few questions.

When choosing new RAM, obviously I can't buy PC ram, it has to be Laptop ram, but are there different kinds of RAM to be careful about, like different voltages, pins, etc?
I know my laptop model, it's a Toshiba Satellite Pro u400 (.pdf spec), if I were to buy from say, Novatech (ram page), which options would be a no go? Or would I have to buy specially designed RAM for the laptop?

That also brings me to my new question, if I were to install 4gb of new ram on my laptop, that would give me 2x1gb spare that I'd want to put in my mum's laptop. (She's running Vista with 1gb)
Would I be able to just take out my Laptop's ram, and safely put it in hers? She is using a HP Compaq Presarion F500 (.pdf spec). I know it has 2x512mb RAM.

So, can anyone help? I'd appreciate it a lot.

 

[Law]

Welp, PDF specs say they both take PC2-5300. Ignore the previous message, I guess the site that google gave me was out of date. One says SODIMM and the other says SDRAM though, and I'm not really up to date on laptop ram either.

Could just take the RAM from your mothers out and the RAM from yours out and compare them.

 

[Bloodgod]

PDF says PC2-5300 max capacity 4GB. I'd go for 2x2GB ram. Since you're Vista 32 bit you'll only see 3GB (IIRC). But do what you want.

http://www.newegg.com/Product/ProductList....p;Order=REVIEWS

 

[RupeeClock]

PDF says PC2-5300 max capacity 4GB. I'd go for 2x2GB ram. Since you're Vista 32 bit you'll only see 3GB (IIRC). But do what you want.

http://www.newegg.com/Product/ProductList....p;Order=REVIEWS

Well that helps, yeah I know about the 3gb limit but every little helps.

By the way, newegg don't ship to UK.

Edit: I just opened up my laptop and it looks like I actually have one stick of 2gb, that changes everything.
It looks like I only need to buy 1 more stick then. That also begs another question, is it safe for me to mix two different brands of RAM?

Edit 2: CPU-Z is telling me that 2gb stick is running at 333Mhz, and not 667Mhz. Does that mean it's slow RAM?

 

[RupeeClock]

Apologies for the bump/doublepost but I still need some answers about using 2 different brands of RAM.

Can I just add a new 2gb Stick next to my existing one, or will I have to replace it with 2 new 2gb sticks?