They are two very different beasts.

PPC is like any other marketing campaign, you spend money to make money for a targeted product or service. This is a near immediate result.

SEO is optimizing your content to bring in traffic from Search Engines. You may or may not spend money on this, and the results are long term, but slow in coming.

SEO is not a replacement for PPC, and PPC is not a replacement for SEO. The needs for each one are different, and each have their uses.

For Fast Result PPC will be good but it will make cost.
SEO is time consuming process but can give you free traffic for long time.

if you have the money, try to do both. PPC first for instant traffic then SEO for serps and long-term results