Not a lot of people are in support of registry cleaners, but really. Any sort of program such as the ASMW PC-Optimizer that deals with the registry and small Windows XP tweaks can go a long way. Another thing is if you open up MSCONFIG (Run -> msconfig), you can go to services and shut off countless numbers of services(processes that take up a useless amount of RAM/CPU) that you don't need. That'll be the most software enhancements you could do, not many other things other then stop most/all start up processes because honestly, half the things that start up, you don't really need. Just have an antivirus open, and that should be pretty much it.
Hardware specs are all related to your hard drive, RAM, CPU, GPU, motherboard itself, etc. Being as how you are on a laptop, the only real upgrade you could do would be in RAM. GPU is onboard for the most part, and CPU can be upgraded but that's a more expensive component. The end all is the fact that you are on a laptop. Laptops aren't meant to be power stations, and more often than not, have been developed with power and efficiency in mind. Any upgrades would result in a loss in battery life, and/or more heat generated etc.