Why are laptops bad for gaming?

Is there anyway to get them running new games (battlefield2.etc) ?

They're much lower end. Smaller harddrives, less memory, small graphics card, etc.
They're designed for work, not play (Which, IMHO, sucks)

The majority of them are you mean?

I've seen laptops with 512/1024mb ram and can you not just replace graphics cards?

In most cases (99.99%) you cannot replace the graphics card.
Much slower hard dirsk drives, most of them ship with 4200 drives, though some do with 7200. Even so, they are still slower than fast 3.5" drives.
Graphics cards, even of the same model as the desktop equivelant, are slower.
Memory can be usualy slower.
The CPU is slower, though for example the most recent Pentium Ms are faster per clock from their desktop Intel's, they are still slower in terms of speed. The myths that see 1.7Ghz run faster than 3.2 is that, a myth.
They are far more expensive gaming speed for gaming speed than a desktop.
The sound cards are much worse than what you can get for a gaming desktop. Though there are external options (USB), that would mean extra strain on the resources (USB). Still, they are not even close to say the new Soundblaster X-Fi range.
Motherboard/mainboard cannot be changed, thus upgrade in the future (say a couple of years) is a no no. So, if you spend lie 2000 GBP for a very fast gaming laptop, after two years (or later) you will just not be able to upgrade it to make it "new" again, thus need to buy another expensive laptop. Where if you buy say a desktop for 1400GBP that will probably anyway defeat in performance that laptop, and in 2 years time you want to upgrade say maiboard and cpu, it could cost you like another 300 GBP. Without considering of course if you want to upgrade the graphics card.
Usualy limited memory slots, which in most cases are full anyway.
If one thing goes wrong (graphics card, cpu, sound) you are stuck without a computer till replaced or fixed (which depending could take a long while), where with a desktop you can usualy not only diagnose the problem yourself but also replace the malfunctioning hardware yourself as quickly as possible. (or of course if you do not mind waiting, send it to the company that sold it to you for repairs)
Anyway, there are a few more reasons (for example limited monitors etc) but those are the main ones I think.
And yes, I did buy a gaming laptop a few years ago that I still use but I wish I had bought a faster, more powerful desktop with less money.

I agree with efthimios.

The question is the power consumption: a laptop which use 50 W (well, i don't know a laptop power consumption, but the example should work...) can't make the same things of a PC which wastes 400 W !!!

and the keyboard is unpractic=)

Thanks for all your comments.

What you've said makes sense and has answered my question. I've often heard people talk and complain about laptops being crappy for gaming but never quite understood why. Thanks for clearing it up!

-

Sean

my laptop works quite fine for gaming ...

I have a Cnetrino Pentium M 740 with 1.73Ghz, 1024 MB RAM and Radeon X700Mobile with 128MB (real) memory and I cannot say that it is more slowly than my other 3200+ AthlonXP with the Radeon 9600 XT4 256MB. The only thing that sux is that those notebooks cost a fortune and are completely outdated after a year or two 'coz you cannot upgrade major parts ...

wow swiss, tou look a bit walthy=)
...wanna meet? LOL

my boss was so nice to buy me the laptop ... you an apply for a job at our company - we'Re still looking for new skilled and motivated employees... :w00t: