As already mentioned, the more RAM you have, the better your computer will run. You will be able to perform more tasks and do them faster if you have plenty of RAM. Actually, upgrading your RAM to a higher level will usually give you a whole new computer. There are recommended minimum requirements if you want to run certain programs or operating systems on your PC or Laptop. For running Windows XP, Microsoft recommends 128MB as the minimum RAM requirement, again more is better.
For Mac OS X systems you will need a minimum of 128 MB but for optimal performance try 512 MB. Linux will work nicely on a system with only 4 MB of RAM.
For Windows Vista – Microsoft recommends at least 1Gig of RAM but many users have reported that 2 to 3 Gigs of RAM makes Vista a much more easier beast to handle. Vista probably needs all the good press if can get.
Again the more the better, gaming laptops need a lot of RAM since you have heavy video graphics and images. Serious gamers usually buy as much RAM as they can afford, choosing the fastest machines with the latest Graphics Card. Laptops with four Gigs of RAM are becoming common, with many gamers opting for 8 Gigs.
At the time of writing, what levels are we currently at in regards to laptops and RAM? Well, the new Alienware Area-51® m17x Notebook comes with the following specs: An Intel® Core™ 2 Extreme processor with up to 4GB DDR2 667MHz memory, sporting Dual Nvidia® GeForce® 8800M GTX. This machine also has the Killer™ K1 Gaming Network Card plus the ultra-life-like environments generated by the Ageia PhysX™ processor. You should also note that Ageia was recently (Feb. 2008) acquired by Nvidia.
Perhaps, in regards to RAM, the wisest route to take is to buy a laptop or PC where you can easily upgrade or expand the RAM if you need more memory. Changes are, wait a few months and you will probably need to increase your RAM.