Eyefinity is ATi's technology of using three - six monitors, either all as one, so it either becomes a massive screen, or each screen can be used indiviudally. I'd go for the Core i3 330M laptop. Somebody correct me if I'm wrong, but the difference between the two CPUs in both laptops is that the Core i5 430M has Turbo Boost, and can go up to 2.53GHz, while the i3 330M stays at 2.13GHz, and I'm sure that the 400MHz difference in clock speed won't equate to too much of a performance loss with regards to having 11 windows, 10 tabs on Firefox, and Skype. I don't even think the Mobility Radeon HD 4330 supports more than one monitor, unless you use your laptop display as one monitor, and an external LCD or projector as another.
From AMD's website:
ATI Eyefinity multi-display technology
Four independent display controllers
-Drive up to four displays simultaneously with independent resolutions, refresh rates, color controls, and video overlays
-Combine multiple displays to behave like a single large display
Go for the Core i3 330M and ATi Mobility Radeon HD 5470 laptop.