The problem with a geomagnetic storm is that it will induce currents in conducting objects, such as power lines.
A geomagnetic storm shares some properties with, but it is not, an EMP. Or better: what we think of as an EMP is a very localized phenomenon, which at relatively close range has energies orders of magnitude above the ones of a CMU that happened 150 million kilometers away from the Earth.
So an EMP like STARFISH PRIME's would trash your equipment if it happened within a few (tens of?) kilometers, depending on shielding. A geomagnetic storm will induce currents that are proportional to the length of the conductor coil. While this is very bad if you're a power station connected to a 500 km set of wires, it is next to harmless if you're a home PC no wider than a few tens of inches.
But telluric current protection is in effect on most power lines since the bad period in the 1990's, and hard disks and the like are lightly shielded against everyday magnetic interference.
Only the severest magnetic storms are able to pierce Earth's magnetosphere, in which your hard disk lives immersed. It follows that only rarely a magnetic storm will develop local strengths of more than, say, five times Earth's magnetic field, which is around 0.50 Gauss.
And hard disks (and consumer electronic equipment in general) are largely immune to fields up to six hundred times that.
For example, in RAID disks, you'll have DISK 2 which is spinning very close to disks 1 and 3, which come equipped with very powerful rare earth magnets. From 2's point of views, those two magnets are an interference and a harassment, yet RAID disks perform flawlessly for years.
Additionally, desktop PC are usually encased in a steel or iron case which is not only antistatic (a Faraday cage) since it is metallic, but it is also antimagnetic since it's made of ferrous alloy. Laptop PCs have lighter alloy cases (from most to least expensive, titanium, magnesium, aluminum and plastic) which are not antimagnetic (plastic is not even antistatic - or not very much even when the inside is surface treated with conductive paint).
However, there are magnetic shielding cloths that will increase your equipment's resistance to solar flares by anywhere from 2 to 7 orders of magnitude; I remember seeing an antistatic/antimagnetic/RFID-proof case for Mac Air on Amazon, so I'm pretty sure they should exist for other models too.