I have installed FS Protection on a Windows Vista 32bit. It handled installation process properly, even uninstalling f-secure Internet Security Technology Preview what was failing on Windows XP.
Since windows Xp official support has been dropped from Microsoft it is unsafe to use. This is a reason why F-secure has dropped their support from it too since they cant guarantee that it will work right. Also there might be holes that hackers use that arent fixed anymore.http://community.f-secure.com/t5/End-point/Support-for-Microsoft-Windows-XP/td-p/42073"Dear all,As you may be aware already, Microsoft will stop supporting Windows XP on 8 April, 2014.F-Secure business licensed products - F-Secure Client Security and F-Secure Anti-Virus for Workstations - will support Microsoft Windows XP with SP3 platform until the end-of-life of the 11-series products as stated on this page: http://www.f-secure.com/en/web/business_global/support/supported-products.F-Secure PSB Workstation Security, a part of F-Secure Protection Service for Business (PSB), will cease supporting Microsoft Windows XP at the same time as the business licensed products.F-Secure highly recommend customers to update their operating systems and use only Windows versions that receive security updates from Microsoft. The latest operating system version always provides the best protection technologies, are fully maintained by the vendor and receive timely security updates and improvements. F-Secure cannot guarantee the best protection and performance for customers running Windows XP after April 8th, 2014. This is because malware can use vulnerabilities in the operating system that are no longer fixed by Microsoft."