I haven't read the magazine for a couple of months, so I may have the wrong end of the stick here.
Did the person with the query mention the make & model of the PC or motherboard. If so then the advisor would have a good idea whether the mobo had a PCI-e or AGP slot, as not all boards have these, especially the low end boards with integrated graphics chip-sets.
As for PCs that won't start, there's a number of reasons for this, and the answer depends on what stage the PC is stalling.
If it won't start at all, then the most likely culprit is a dead psu, but it could also be down to a faulty case - the wire could have come off the power button.
If the PC powers up but fails POST (Power On Self-Test) you'll get a series of beeps, these will give you a clue about the faulty component - RAM, CPU, VGA Card, North Bridge etc.
If the PC gets past POST then the OS is the most likely candidate, either one of the drivers has failed or become corrupted, or the registry has become corrupted. If the former then starting in Safe Mode is favourite, then checking the drivers, but if it's the registry then using Windows System Restore to go back to a previous configuration is a good idea. This won't delete data, but may well restore the registry & drivers to a previous working state.
If this doesn't work, then using the Windows CD or restore CD from the manufacturer should do the trick, but will obviously wipe all data and software, which is why regular back-ups are a good idea...