Been at this for a couple of hours. Tried re-installing Java with no avail, Control Panel>Java seems to do nothing when I change it, and when I launch the regular Minecraft launcher trying to allocate more ram with the Xmx Xms arguments, I get this error:
Error occurred during initialization of VM
Initial heap size set to a larger value than the maximum heap size
Picked up _JAVA_OPTIONS: -Xmx512M
Windows 7 OS, JRE 1.8.0_20 + 1.7.0_67, and yes, I already tried Googling it.
EDIT: Here's the pastebin, for any of you interested in it; http://pastebin.com/Dkspakhf And I did 'java -version' on cmd, and guess what: "Picked up _JAVA_OPTIONS: -Xmx512M" haunted me there too.
EDIT 2: Solved.