On Vista Home Premium Notebook, Will I get a Performance boost from adding 2 GB RAM?

I own an HP Pavilion dv9000 that came with 1GB of Ram. I have added another gig bringing it up to 2GB. But I can replace the 2 existing RAM sticks with 2GB sticks.

If I boost it up to 4GB can I expect a performance increase? If so, is it enough to make the purchase worthwhile? Thanks
Update: Specs: AMD Turion 64 X2 Mobile TL-50 1.60 GHz

32 bit Vista home premium

120 GB SATA hard drive

Nvidia Geforce go 6150
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