Actually, every laptop I have opened to date does not have the CPU soldered on. QL-60, TL-50, Pentium 4, and one other I can't remember.
Just be careful of the cooling. If the laptop wasn't designed to handle the higher model...
If the model did not originally come with a model of your laptop, the bios might not support it aswell.
As for finding one, if you do it will be overpriced and not usually worth the upgrade.
So if the cpu works in it, it will be a "simple" out-in. Just pay attention to thermal compound. Sometimes, like on my TX2500, the HSF will not actually be making very good contact with the CPU at all. I ended up having to apply a ridiculous amount of thermal compound because of that.
Also, there is the matter of taking the laptop apart. The last laptop I know of that had a bay to allow access to the CPU was from like 2005. So you will have to take apart the entire chassis and pretty much take the motherboard out of the laptop in order to access the HSF and remove it. Don't lose any screws and keep track of where things go.
I was just merely stating that some laptops can have the CPUs soldered down, not all
I know I might be looking at updating the BIOS and will be looking in to that shortly. I can pick up a dual core CPU for around £50 or so meaning the increase from a Celeron M 430 to a Dual Core 2 ghz will be quite something!
My laptop is VERY easy to take apart actually and can access the heatsink + cpu combo very easily!
The laptop did come with a dual core processor at one stage in its life, but I cannot find out which but, as the newer processors run cooler anyways, I'm pretty sure that the only issue I need to work out would be to see if my BIOS supports, or, can support, a T7600