Either from here: https://bitcoinxt.software/
Is there any particular reason why you recommend a newbie Bitcoin XT?Currently it doesn't make that of a big difference. If OP wants to run a full node, both XT and core will be participating in the network similarly for a minimum time until (January 11). Of course running bitcoinXT shows support towards Gavin's and Mike's proposal for the block size in a way but still doesn't affect the outcome of the voting mechanism that is effective after January.
newbie question for you: I have core. On Jan 11th of next year if the vote goes toward XT, will I have to download XT client software or will there be an update for core to handle the increase in block size?
I'd say wait a little and see how this develops. It's very likely that we'll know what's going to happen ahead of this date. But trying to explain all the possibilities could get complicated and confusing. Don't worry though, neither of both sides is aiming to destroy bitcoin.
