I have trouble with the memory Minecraft uses when I play on far (I like to play on far)I have 4 GB ram so It be should enough. I tried something they sugested on the IRC (from the minecraft page) making a textdocument in the folder with Minecraft and pasteing some codes in there and changeing the allocated memory but that didnt help. If you have any sugestions or tips please write them.
-Error http://i.imgur.com/t6Ylu.png
-Frodi

Are you using the .exe version of minecraft or the .jar?
Try the jar and run it like this:

(you may need to directly speficy the path to your java.exe, like C:\program files\sun\jre1.6.20\bin\java.exe, if the path has spaces, surround the C:\...exe part with "")

If you feel like trying to get the most performance out of java add these parameters:

Replace the 8 in "ParallelGCThreads=8" with how many CPU cores are available.