Supports: "DDR3 SDRAM (1066MHz) 2 slots supporting 1GB, 2GB or 4GB DIMMs"
Click here for spec sheet
I'd get this kit from G.Skill:
On newegg.com
You could get other kits for about $5 less but G.Skill is a name I recognize so I think it's worth slightly more.
*You'll need to check if you have 32 bit or 64 bit windows looks like that laptop might have come with either depending on options chosen? If it's not 64 bit and you want 8GB of ram you'll have to upgrade windows first to be able to use more than 4GB.
Edit: Yeah I checked both the processor options listed in the spec sheet and they both are 64 bit processors so if you need to upgrade Windows you definitely can.