Well, I do have a desktop pc which is around seven months old now. I build the pc from scratch. So far, I have no problems with the hardware and softwares but I have to say that the pc is in tip top condition, thanks to me. I am writing here to give you some tips about pc maintenance.
If you do have a desktop pc, make sure you place your tower in a well ventilated area. Placing the tower in a secluded area without much ventilation will see that the temperature of the pc will increase and you will be able to hear the fan moving faster, hence increase in noise.
Apart from that, it is always good to use the vacum cleaner to suck the dirt from the inside of the tower itself.You will be able to find a lot of dust around the cpu and also the PCI-E slots, not forgetting PCI slots. Please make sure that in whatever you do, please switch off the pc and move the tower away from any electrical points and uses an anti-static matt before you ever begin cleaning the tower.
In regards to the HSF, you can actually dissemble it nicely and use tissue and a little bit of water to clean away the dust around the fins of the fan. Please use a vacum cleaner to suck the dirt out from the heatsink. If you prefer, you can also use a spray can of air to drive away the dirt within the heatsink. After doing that, you can re-assemble the HSF and fix everything back into order before switching it on again.
Priodical checks and maintenance of the pc will ensure that your pc will run in tip top condition.
If you have a laptop, switch off the laptop and unplug the laptop from the mains. Remove the battery (if any) and use hte spray can to spray directly on the heatsink outlet. You can also use tissue and a little bit of water to clean the fins of the heatsink. This can only be done if you are an expert. Don't do it if you don't know how to do. You do need to use a screw driver to open the back panel of your laptop before putting it back on.
Regarding Windows OS, what is necessary is that you do defragment once a while and uninstall all unecessary files. In that case, you will be able to save space. Always have an up-to-date antivirus definition and firewall system for your pc. In that case, it will at least protect your pc from potential hackers and viruses including trojans.
I believe Windows Vista is well matured to take over Windows XP. However, there are many softwares which are written specifically to support Vista only or XP only, hence the problem over here. Wait...Windows 7 is arriving soon! What about that then? I think I would just stick with Vista Home Premium for the moment. I do find that in using certain bechmark, XP is relatively faster than Vista but it does not matter as I have bought Vista a week before it was launched last year.
One last thing. Make sure you perform windows update to update all critical updates for windows operating systems and also possibly drivers for the graphics card and soundcard.