Resolved How to assure RAM compatibility in a laptop?

I have a Dell Inspiron N5110, running Win 7 64bit. It has a 4gig SoDimm in one slot and one more empty slot. It can handle up to 8gigs total. Acceptable RAM totals are 2,4,6, and 8gigs.I don't want to degrade the overall performance by buying cheap or incompatible ram. I understand that the motherboard will run at the slower ram if it is presented with two different sticks. Am I correct, or is that only with older computers? CPU-Z identifies the ram as Hyundai CL9.
The owner's manual simply states that the ram should be DDR3 1333Mhz.
The SoDimm in there right now is a Hynix. The label reads "4GB 2Rx8 PC3-10600S "
The second row reads "HMT 351S6BFR8C-N9 NO AA." There are two rows of 4 chips per side of the dimm, for a total of 16 chips.
I went to pricewatch dot com, and the cheapest stick is a generic that goes for $22.45 including shipping. The next step up is Super Talent, then Kingston, Wintec, Rendition by Crucial, and Corsair, and the prices on these is only $2 to $3 more.
I don't mind spending the extra money if it insures me compatibility. From there the prices go up dramatically($10 and more), but it seems that they are the same dimms that others sell for $25+/-.
I read some reviews about Super Talent, and they were most, if not all, positive.
I never hear of it, but that doesn't mean it's not good quality.
So, if you are an expert in this matter, which DDR3 1333Mhz 4gig sodimm would you choose, knowing that the other one is a Hynix HMT 351S6BFR8C?
Thanks.

 

Hi skaler2k, The best would be to get a Twin Pack from Kingston or other makers who offer Twin Packs.
As long as the RAM is exactly the same in all details - it will usually be OK.
I have a mix of 3 Brands in this comp which seem to work happily together and have been for at least 3 years. Cheers Neil.

 

I ended up buying a 4gig SoDimm from Newegg after using CRUCIAL's ram matching tool. The price was right, and having seen the Hynix stick with my own eyes plus the info that CPU-Z gave me-CAS 9, two rows of 4 chips per side, etc,
I'm pretty confident that it'll work. Thanks to one and all who responded.