Seeking Arial Italic!

Hello:
I was trying to add Arial Italic in Gimp just now,,,only to discover that I don't have Arial Italic on this iMac! I checked the Font Book and it's not there.
Does anyone know where I can get this font? Do I have to pay for it??
Thanks very much.

It seems you do have to pay for it:

http://ascenderfonts.com/Merchant2/merchant.mvc?Screen=PROD&Product_Code=ARI01-02-02-05&Category_Code=ARI01

Hmm...my mac has arial italic...Is helvetica not close enough?

no, unfortunately...I had done a logo for a small business when I built their website. This logo matched their letterhead exactly. I simply wanted to use GIMP to make their current web logo look better. That's why I need Arial Italic. You question is logical though---lol