Yep, I already got some comments on that. You are either using a 32 bit system or a 32 bit binary (at least I think that the binaries PHP distributes for Windows are compiled for 32 bit, so even if you are on a 64 bit Windows you'll still get 32 bit numbers).
The Windows number still is 8 bytes per element larger than the number I wrote (76 per element). This might have various reasons, one could be that it was compiled with head protection :)