Hook for detecting file access

[thomas49th]

Hi, I was wondering if anyone can point me in a direction of a (ideally free) program that detects if an process/executable/dll is accessing a file on disk - or even better all the files currently in read/write by process(es). I presume there must be some program that hooks onto a disk storage API and can monitor if any process is reading or writing from/to disk?

Thanks
Tom