Laptop heating up too much after installation of Windows 7

Hello!

I own a HP Pavillon 4710s, and just installed Windows 7 Ultimate x64. Before, there was Windows XP x64 (I think 64, not sure though). The OS was flooded with software and very slow, so I decided to do a fresh install.

I did not choose Windows 8 because I thought it might be too heavy for this 5 year old laptop. Since Vista was the default OS installed on the system, 7 seemed a good option.

After a flawless installation, I started to install Office and so on, everything works very fast and without troubles.

One problem though: the fan is all the time on its maximum speed and the laptop is heating up too much to be normal.
EDIT: Via Speccy, I saw a temperature of 76°C for the CPU and 60°C for the motherboard.
Did I miss drivers to prevent this? Or is 64-bit too heavy?

Thank you very much for your response in advance,

Martijn

How do I find that information? I have to open the case to see that? There is no label on the case of the laptop with wattage indications.

UPDATE:
* I reïnstalled windows, to Windows Home Premium 32 bit
* I cleaned the fan by unscrewing the laptop, the fan is running normal now (after it had stopped working completely). However, I could not see the PSU unless I completely demounted the laptop.