What would be the best Windows OS for me to buy for a 15-inch: 2.4GHz Intel Core i5 4GB Memory 320 GB hardrive? I'll be using it mainly to run some online poker third party software that can only run with a windows OS. A pro on youtube said he decided to use XP for his MAC since it required less memory. However his article was in 2009, so I'm not sure if Windows 7 would be better and more up to date. I'll be using parallels as well. My biggest concern is slowing up my computer or not having it run smooth. Should I get XP or windows 7? Please be specific. 32 or 64 bit, and what version, Home, Business, Ultra, etc. Thank You in advance.