Well, I recently bought a MacBook Pro after the last refresh and I love it for it mobility. But if at home I really like to work behind a desktop. Im thinking of buying an iMac but I do now know if I should buy the i5 or i7. When I ordered my MBP I choose the i7. Is the i5 in the iMac twice as fast as the MBP i7?
Will i5 do fine or is it smart to order a i7 for these tasks:

Well im almost sure the answer will be i5 but isn't smart to order the i7 because it "only" 170 more? or will it be better in my case to double the RAM and not update the chip?
Thanks for the information.
Will i5 do fine or is it smart to order a i7 for these tasks:
- MSN (Almost every day)
- Itunes (Every day)
- Firefox and/or Chrome (Every day)
- Photoshop CS5 and/or Illustrator CS5 (Almost everyday)
- Textmate (Almost everyday)
- FTP program (Almost everyday)
Well im almost sure the answer will be i5 but isn't smart to order the i7 because it "only" 170 more? or will it be better in my case to double the RAM and not update the chip?
Thanks for the information.