There are so many different laptops out there that it would be best to have have some one with a laptop near the specs you are getting and test to see if it is going to be able to play Minecraft. No one here on the forums can tell you if a certain computer will play Minecraft.
I have a pretty cheap laptop (Toshiba Satellite, 64 bit, 3GB RAM), and I can play Minecraft just fine. I used to have lag issues until I installed Optifine, and that fixed things right up. I still have some lag issues in taiga and jungle biomes, but nothing that makes the game unplayable. I do have to play with the distance set to short, however.
The touchpad was kind of annoying at first, but I got used to it pretty quickly. If you don't like the touchpad, though, you can always just plug in a mouse.
EDIT: I should also mention that I only play singleplayer, and I don't use a lot of redstone. Large redstone contraptions tend to make it pretty laggy.
I use a laptop, and I used to play on PvP servers, so the pad clicking was difficult, until I changed the 'Attack' button. That seemed to fix it. And also, lag problems don't happen on my laptop very much. It's usually the server I play on. When I run SSP, it works just fine. So no, unless you get a really crappy laptop.
Rollback Post to RevisionRollBack
"... I thought that his skin was a cow."
I play Minecraft on a laptop all the time with minimal lag in most situations, and I use a USB mouse so I'm not stuck with the track pad. However, I'm usually restricted to short render distance, but I'm alright with that. Normal render distance doesn't particularly lag me, but it spontaneously crashes for no apparent reason after a few minutes, so I don't typically play on it. My laptop is also stuck with an integrated Intel graphics card, so there are certain issues that come with that too.
At any rate, it all depends on the laptop you buy.
It really depends on your needs, I got a laptop for my gaming needs but I also needed a very powerful laptop for my school needs. I got my laptop for around 980$ and i find i can play minecraft with around 200 FPS smoothly with no problem, that being said. You could get a PC just as powerful as my laptop for nearly 200-300$ less. But if you are looking for a strong utility laptop that does not cost extra money because of flashly apperences I would recomend checking out the company ASUS, they have very powerful systems that are also relatively cheap because they don't shoot up the price to 1,400$ just because it "Looks Cool"
It's not that difficult to use a laptop for MC. I've used one with a graphics tablet mouse (Wacom Bamboo Pen vers.) with no issues. It's the RAM/processor which might cause issue. My Toshiba Satellite died recently due to overheating - so get yourself a good fan and take breaks to preserve the life of your laptop...