LOL, two instances mined a block I just see, both were rejektet
What kind of bad luck is that, two in a row rejektet

User are trained to look for cpu usage and not memory so it won't matter if you start one xpm thread with low memory usage or one proto thread with 700 mb memory, even finding a blocking process is beyond many users capabilities. Even quads are uncommon in offices so the sneaky sysadmin woulnd't start more than one thread anyway, thus the 3 threads limit is ineffective.

If you are a datacenter admin on the other hand, both doesn't bother you since you're either running linux or just spam instances.

But we are going offtopic  

I5 2300 with memory 2g can not mine

At least, 4g is necessory

How do you see this?

Are you sure you can easily and invisible use the 32-core server and tons of office computers with 1-2GB of RAM when you need to install a QT for each of them?

Million thanks mate - apologies for being so newbie in this...

Is "setgenerate true 2"  not necessary? So is the Mac version mine by default?

I see that this is a normal generated block.
Here is my list of transactions:
{
"account" : "",
"address" : "PqMJ4EejT8QNSLXjFNMA7arSWWFsbVU1wX",
"category" : "orphan",
"amount" : 50.00000000,
"confirmations" : 0,
"generated" : true,
"txid" : "79466661536f01902308dd29b89366523dbb1fc6221f335468c8f0a3378bfd89",
"time" : 1383648052,
"timereceived" : 1383648070
},
{
"account" : "",
"address" : "Pa2iUervGAchNAmzQSup6PQG2jm1SMQTip",
"category" : "immature",
"amount" : 50.00000000,
"confirmations" : 95,
"generated" : true,
"blockhash" : "00010778425538d90872d757a1fd85408cb4bffb47a735c338ab554fd10f0cf0",
"blockindex" : 0,
"blocktime" : 1383658879,
"txid" : "07dc812c01cc0357c78c70ef23d5dca05a0b8caaf42ed770c8908a8d70f663b4",
"time" : 1383658879,
"timereceived" : 1383658896
}

Well, I dont use the same wallets on may instances any ways, all different wallets and block chain in a different folder...
but thanks for the advice

1 block here!