ExtremeTech has a guide on building a $2,000 desktop PC for Adobe CS5, you can check it out over here.
Some advances over the last year have made faster and more efficient computers possible for less money than you may have thought possible even 18 months ago. This isn't to say that putting together a system that can blow through any Creative Suite 5 (CS5) app with ease will be a wallet-friendly process. Especially if you're into high-level video-editing and movie-making, it won't be—for video-related reasons we'll get into in a while. But for less than $2,000, you can assemble a professional-level system that can handle almost anything you and CS5 can throw at it.