Gosh, this thread is still going, and the holes is still not drilled!
I own just about every one of the drills suggested above, and each has their own pros and cons.
A conventional twist drill of half an inch is likely the easiest idea. It is the drill that will be most useful after you buy it. Just get one with a reduced shank. When drilling it will be worthwhile pre-drilling the hole with about a 1/4 inch drill. The point on the 1/2 inch is not a point, and pre-drilling will stop it wandering. Particle board is prone to bad behaviour, and whilst pre-drilling in ordinary lumber is not needed, pre-drilling the particle board may help the drill staying on course. Not that it really matters in this use.
A conventional drill will however almost certainly split out the backside of the hole in particle board. This probably doesn’t matter but is unsightly. Drill from both sides using the pre-drilled hole will help mitigate this.
A hole-saw is another possibility, with care. A 1/2 inch hole is small for one of these. They are bad at clearing chips, and need constant removal to clear chips. However if you drill a smaller hole on the circumference of the desired hole that the hole-saw can clear chips into it works vastly better. You can start the hole with the hole-saw to just touch the surface and mark it. Then drill a say 1/4 inch hole inside and intersecting the saw marked cut, then start with the hole-saw again. The chips will be driven into the hole and fall out of the work rather than gumming everything up.
A spade bit will work, but in particle board they have a terrible habit of trying to cut a triangle once the pilot point is no longer well anchored in the wood. The particle board is likely to start to disintegrate before the hole is done. and the drill may start to go nuts. Again, drill far enough through so that the pilot just exits the other side, and then swap to drilling from the other side, and go slow.
The hole saw will usually give a good edge, as will a carefully used spade bit. A conventional bit will risk tearing the edge.
But just marking out a hole, drilling a heap of small holes with the drills you have and if you have a suitable file, cleaning it up with that, is a perfectly acceptable answer and a time honoured one at that. A technique that is hard to beat if you need anything other than a perfectly round hole.
The best drill is often the one you already own.