On my Win 7 machine I use an application called WinAFC just because I don't want to turn off the security settings. On Linux, there are a couple of posts some time ago about how to set affinity, but it basically boils down to using two different commands to launch the two different instances of the client.
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Remembering Tyneetryk
Phaedreas Tears - 15 years old and first(*) of true neutral guilds in Atys.
(*) This statement is contested, but we are certainly the longest lasting.
<clowns | me & you | jokers>