VLOOKUP Product numbers and price lists

Hi Guys!

I am new to VLOOKUPS, I saw our finance guy use it the other day and this is what I need to save tons of time on a few projects I am currently working on. I hope someone can teach me how to do this.

My goal is to add previous years pricing by searching by product codes. I could simply copy and paste however items get cancelled every year and new products get added so they never line up.

So here is what I am working with:
I have 2 Workbooks: "2009 Price.xls" and "2008 Price.xls"
Worksheet are both called "SKU"

I want to find product by product code with price and and price to 2009 pricing book

Product Code is in column A and the Price is in Column B

Can I do VLOOKUP within different workbooks?
What formula would you suggest?
So if the previous year I had 500 products and now I have 450, I want to line up the ones still available.

I hope this makes sense.

Thanks
marc