Well, the reason why I think I'm running low on memory is because when I have a VPN session on and I type in 'java' (needed for jDownloader) in the console, I get the following error:

Error occurred during initialization of VM
Could not reserve enough space for object heap
Could not create the Java virtual machine.
However, if I restart the VPS and do not start the VPN service, and instead just login through ssh again and type in java, I get the correct response (all java parameters listed, etc) ...

So how can check this out ?

I tried to use 'free', and the output I get is this:

root@server1:~# free
total used free shared buffers cached
Mem: 4294967292 190300 4294776992 0 0 51608
-/+ buffers/cache: 138692 4294828600
Swap: 524288 0 524288
root@server1:~#
And I'm not really sure what this means ..