Data transfer between two PC's (hardware)

My wife got an old computer from work after they upgraded. It's a 2008 Windows 7 Lenovo but a big upgrade from our 10+ year old HP with XP. It was too old/slow to even play video and had no sound card.
Anyways, I'd like to copy data between them but only have one monitor. Can I run them both at the same time networked and swap the monitor back and forth to transfer stuff?
Would unhooking the monitor while PC's are on be an issue?
It would be easier for me to copy files directly rather then using our external drive.

 

I would advise against hotplugging the monitor. Also, I'm not seeing how it would be easier. MS has this for data transfer for those moving from XP to 7: http://www.microsoft.com/windows/en-us/xp/transfer-your-data.aspx

 

Thanks. Wouldn't that still be tough with just one monitor though? Can I boot one of the computers without a monitor and access files on it from the other?

 

Well I started the XP machine without a monitor and I'm transferring directly over now.
Seems to work good enough.

 

Wouldn't a KVM switch (you aren't forced to use KM bit) do the trick ? They are only a few quid

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6.February.2015