Core i3 and Core i5 Processor

I have a laptop with a Core i3 processor as well.

As there are several versions of these processors currently available in new systems, it is difficult to compare them in a general way but I'd say the following are the main differences:

The i3 always has 2 cores, the i5 may have 2 or 4.

The i3 always has 3 MB of level 3 cache, the i5 may have 3 or 6.

The i3 doesn't support Turbo Boost (the ability to dynamically increase the CPU's clock rate) but i5 does.

The i3 doesn't support the AES instruction set (which improves AES encrytion/decryption performance) but i5 does.

Basic CPU clock rates are usually higher for the i5 than the i3.

Unless you run a lot of CPU-intensive software, I don't think I'd be in a hurry to upgrade your system. The release of Windows 8 later this year, for which a multi-touch screen will be desirable to run Metro apps, may be a more opportune time.