Right off the bat let me say as a 100hr ppl I'm not trying to disagree with the instructors views on here about e.g. instrument fixation, but just offer a couple of things from my experience.
1) Having played with PC jet fighter flight sims long before I got the bug to learn to fly, I
knew(
TM) that stick forward was down, stick back was up and throttle faster/slower. When I started following the built-in lessons in FSX, it took me a while to break that and relearn forward faster, back slower, throttle up/down approach technique. Using the sim I was able to break the old and learn the good new technique before I even got around to starting lessons. I'm very glad I did that rather than pay an instructor rate to do it. I don't think it made instrument fixation any worse than it already was from my previous "playing" (you
are allowed to play with computer sims before you know you want to train to be a pilot
)
2) I bought a second hand full cessna control set of yoke, throttle and rudder pedals. I sold it after finishing my training for pretty much exactly what I paid for it, so no cost to me to have it for 3 years or so. With that I learnt to use the rudder pedals instinctively. As someone who grew up on a pushbike, the pedal steering in a plane felt back to front for me. Again I'm glad I retrained the brain on that for free rather than instructor rate.
3) I got photo-real scenery and rehearsed nav exercises both before and after I had done them looking for landmarks and never looking at the sim map display. It's easy to forget how hard it is for a new flier to actually recognise there's a bl**dy great town below them and to make out the shape to be able to compare with a map whilst not upsetting the aircraft. All very usefully practised on a PC.
So YMMV and don't think a PC sim will make you a sky god, but it can help learn (or unlearn) some techniques if you use it seriously and don't be tempted to "play" with it once you've decided to learn to fly.
Having said all this, if you've got time on the ground, don't feel the above applies, are confident you are ready for your exams and haven't read it - please use the time to read Stick and Rudder by Wolfgang Langewiesche.
I took the decision not to contradict my instructor by risking reading any different messages and saved reading it until I had passed PPL. But I wish I'd read it sooner. My continuous problems with trim and altitude chasing, whilst they had been improved by behavioural training immediately and completely disappeared with the alternative thinking of trim in this book. You won't regret it.
HTH