The best ways to boost your computer performance without changing the CPU are two folds: 1. Increase your DRAM or DIMM/memory capacity, which serves as a local scratch pads for your operating system and applications. 2. Increase your harddisk speed by changing to SSD (Solid-State Drive or Flash Drive). In this video, I showed you how I upgraded a cheap laptop (~$250) to an Ultrabook by replacing the slow harddisk to an SSD. This laptop already has 4GB of memory and is plenty enough. All it needs is a fast SSD to turn into a reasonably fast computer with a long battery life (> 6 hrs).