Upgrading memory question

[mikehende]

A friend has a pc and he wants to upgrade the memory, he only has 128mb, I aksed him to take out the memory stick and give me the numbers on it but he's afraid to do so. Is there a way to get the details of the memory stick needed from the pc's software? I guided him to the System info screen, he has a Dell PIII deskptop Model XPS T450 System Type X86, I searched for this and came up with

http://www.upgradememory.com/configurator_3.cfm

and also

http://cgi.ebay.com/128-RAM-Memory-Dell-Dimension-XPS-T450_W0QQitemZ220015348862QQihZ012QQcategoryZ162QQ ssPageNameZWD1VQQrdZ1QQcmdZViewItem

How would I know which one of the 2 above will be the correct one for his pc?

[mjc]

Ummm...what is the problem?

Both places are showing PC-100 nonECC RAM. Basically the same thing.

[mikehende]

I wanted to know "how" I can be 100% sure that either one of them will be the correct thing for his pc? In other words, what specifically do you look for to know 100% if a memory stick is the correct one?