Which type of page of replacement algorithm is Windows XP and Unix are using?

Windows XP uses the Local Page Replacement algorithm. It is a type of FIFO. In this, Pages are taken from processes using more than their minimum working set and Processes initialize with a default of 50 pages. XP monitors page fault rate and adjusts working set size accordingly.

UNIX uses the Global replacement Algorithm through Modified second-chance clock algorithm. Here Pages are aged with each second and Pages that are not used for a long time will eventually have a value of zero.