If you are Vista user, you sure will know about the problem of Vista. Vista seem like the memory a lot, 1G ram is the minimum requirement for running Vista, else you will found the speed is not satisfied. This is the major problem occur since the Vista launched.
However, one good news here:
Microsoft already develop the Services Pack 1(SP1) to re-cover the weakness of Vista. What you need to do is just update the SP1 into your Vista. Please note that this SP1 can not be automatically updated due to some technical problem. In this case, you might need to update it manually. Do not worry about the cost, this is totally free.
If you do not know how to update the SP1, you can go for below link which showing you step by step.
Blog Blogging: SP1 - Update Tutorial