Computer Question RE: RAM Options

[Mynzeyes]

ok...surely someone on here would be able to tell me...i personally don't see why this wouldn't work, but perhaps someone else can back me up, or disprove me...

i have an HP Pavilion N5445 notebook. factory, it comes w/ 2x128 SDRAM (2 banks, totalling 256 SDRAM). anyway, i want at LEAST 512. max for my laptop is 1gig(1024).

ok..now..the info on the factory RAM is "PC133 SoDIMM SDRAM 144pin" yadda yadda...

my question is, would this right here work or not...i say yes...:
CircuitCity.com - Kingston Tech 512 SDRAM.
ok..that one says "DDR SDRAM", but being PC133 SODIMM, i would think that is a misrepresentation, as stated in the user reviews...

this apparently works, so i figure the one above would as well?:
MemoryX KingMax 512mb.

anyway, i want to get the one from circuit city, because they have it in stock locally, and i can just go pick it up, and that be that...

if you have any comments, suggestsions, etc, feel free. basically i'm lookin for a "yes that will work" or "no, it won't, get the memoryX one."

someone please help, and thanks in advance...

-John-

oh yeah, also...for you computer junkies...i'm running Windows XP home..and since i have 2 banks of 128, if i get the 512, will i be able to mix the RAM cards, and have 1x512 + 1x128 = 640...or would i be better off running the single bank 512, and leaving the 2nd bank empty?

blah. thanks again. .