As a sequel to the previous post Don't go cheap, you have to get the right tool for the right job.
When working on a project, you need a good computer, genuine versions of the softwares and most importantly, a good chair...
It does not seem much to think about, but if you have to be on that chair for several hours a day, you better get a good, comfortable one.
Working with computers and softwares goes beyond processing power, memory usage and disk space left. Your mind may be working extra hours, but your body is also on the same train.
So having a good chair is the most basic requirement as a work tools when you're a making softwares. Have a look around, a good chair can be found for about 150$ at Staples... In an investment in your quality of life and in your physical health.