When I was a kid it used to be all about your processor speed – “is that a 286? No it’s a 386 – woah”. Then as I got older it was how much RAM you had, “you have 512mb! Holy crap!” SSDs have now replaced RAM, get your self between 2gb-4gb of RAM and you are set. If you want more computing speed you need an SSD (see why here, here, and here).

As Patrick Rhone suggests it may be cheaper than you think:

I mentioned this on my personal Twitter account but it warrants repeating here. If one wanted to go extreme minimal Mac, they could easily make due with a 40GB SSD for only $99. For instance, if one used mostly built in apps, used lots of web services, streaming music, etc. the trade of unused space for speed would be a huge win. An Intel model of the same size and price was recommended over the OWC model by a trusted source as well.