Disabling the wrong services ...

can also affect system speed.

Here is a link you can make use of to either reset your services to DEFAULT for your specific flavor of Vista (Home Basic, Home Premium, Business, etc.) or you can make use of what is shown in the SAFE column.

Although you just mention running Vista I hope you do have SP 2 installed and if not you should do so.

You can also take a look in Task Manager and see exactly which processes are using all those CPU cycles. I suggest that because just sitting there doing some web browsing the CPU utilization should be lower than 30 to 45% and you could easily have some malware problems.

It wouldn't hurt to download and run MalwareBytes http://www.malwarebytes.org/products/ and also Super Anti-Malware http://www.superantispyware.com/ and I would suggest running them from Safe Mode the first time.