Of course, partition-only encryption has weaknesses in that the OS may store data in another partition (i.e. you've encrypted the "D:" drive but Windows just dumps a cached file to "C:", let alone the whole pagefile challenge). So you need to trust your OS to not write the masterkey to disk, which is widely acknowledged. I personally run with no page file, so memory ought not to be written to disk by the OS itself (barring a malicious adversary), although this solution isn't the best for someone on 1GB RAM.
Full-disk encryption would block this attack, i.e. encrypted swap on Linux (crypttab makes this quite easy) or system-drive on Truecrypt. Even if it's dumped to disk, you can't get it, again barring online access to the system. Online access this is all null and void regardless as they could just issue commands to dump memory to disk no matter what you've done!