HF is certainly an option, you could certainly get a larger compressor for the money but it's not going to be the same quality as the porter cable. Some people have a strong opinion about harbor freight so it might be worth doing some investigating on what he thinks about them in general.
Here is a equal priced unit from hf:
http://www.harborfreight.com/air-to...hp-125-psi-oil-lube-air-compressor-68740.html
Just to give some general info on what would be the major differences between these units and similar ones;
The porter cable is likely to last much longer and have less of a chance at minor leaking than the HF one. However the HF compressor has a much larger tank allowing longer use of high demand air tools such as impact guns and die grinders ect.
The actual motor/air pump is of a similar size on both units so the larger one will take longer to fill up, something to consider if you might want to use it quickly after it being off for an extended period.
For stuff like filling car tires and running a nail gun both will do that just fine, the porter cable will just turn on more often but it probably wouldn't spend much more time running overall than the HF.
Of Course you could save some money and get the pancake style compressor from HF but I would personally advise against that, I do not have much confidence in their extremely cheap units.
Anyways there's some general info to help you figure out what you want to do.
