You guys are hilarious. Basically this is what you need to take into consideration. With Optifine, and to run pretty much computer lagg free (different than internet lagg) you need 6-8 gigs of RAM. Within your computer settings you will be able to adjust the allocated ram to the game to make it run more smooth. A good graphics card is always something to take into consideration as well when purchasing a computer. As Azie said, 4GB is a bit overkill but it will run Minecraft at more optimal speeds. Bascially any processor over 2.0 ghz will be damn near beast mode with Minecraft as the game is not very computer intensive. I purchased my Mac Book Pro with some good software like Microsoft Word/Powerpoint/Etc, Lowjack and some others including a mouse and external CD drive for $3500 and it runs the game just fine.
If you are spending more than $1500 on a computer for gaming, it best be a laptop because you can get a GOOD gaming desktop for a thousand dollars if you do some researching.
