Hi Angie,
I'm also planning to buy Eurail pass, but my destination will definitely be more than 2 countries (at least 3, so I guess it will be worth purchasing).
If you're only interested in visiting Paris and Italy, then I wouldn't recommend Eurail.
There are lots of (cheaper) options to go to Paris. By train (many trains connection to Paris, just go to train station and ask, no harm just for asking, right?

), plane (easyjet), or even cheaper with car pool system -->
http://hitchhikers.org/index.cgi?fe=...tedridesonly=1 --> this one isn't really hitchhiking since you need to pay, but a small amount).
Just make sure that you book the (plane/train) ticket really in advance to get a better deal.
For Italy, if you want to go to Milan, Venice, or Florence, you can even buy an online ticket with a special price (SBB website --> click and rail, but you can only buy a week in advance and need a credit card to purchase).
http://mct.sbb.ch/mct/en/reiselust/e...raileurope.htm, then click for the option "Click&rail(Italy)". It's only 74chf one way, even only 48chf when you are lucky.
Or...try the car pool system too.
If none of those options work, you can always buy the Eurail and explore more countries

.
Good luck and have fun travelling!!!