The security hole exists in all CPUs from the last 2 decades, so your machines will both be affected.
For now, the KAISER patch will address Meltdown, at the cost of a 30% performance drop. It looks like the Spectre vulnerability is not going to able to be 100% patched, and will require revisions to the actual hardware. No such revised hardware exists yet.
So if my copies of Windows are already up to date - I'm already patched with KAISER and experiencing the performance drop?
Correct - depending on what patch you are running (the public releases do not have the patches yet for most hardware). There is still testing ongoing (primarily by Linux core devs), but it looks like 30% is the performance degradation cap. Some CPU tasks take a smaller hit.
A permanent fix (circumventing KAISER) will have to be integrated into the next generation of hardware.
There are some great NYT security analysts covering the story, that you may be interested in following on Twitter.