lots of them. two I recommend are CCleaner and glarysoft registry repair. Both are open source and free. for a defrag - use defraggler - also free. try sourceforge.net for opensource alternatives.
Registry I'd go for Ccleaner or IOBIT Advanced System Care's inbuilt registry cleaner... Defragger I'd recommend JKDefrag www.ccleaner.com http://www.iobit.com/ http://www.kessels.com/Jkdefrag/
Registry Defragmentation While JkDefrag explicitly mentions defragmentation of registry, Defraggler doesn’t (on its home page), which requires clarification, as it may only be a normal disc defragmenter. Furthermore, JkDefrag requires the PageDefrag from SysInternals/MS. PageDefrag claims to do both, registry and paging file defragmentation: http://technet.microsoft.com/en-us/sysinternals/bb897426.aspx It would thus seem to me that PageDefrag would be a suitable tool to use for registry/paging file defragmentation. • It has been developed by the legendary Mark Russinovich and is officially adopted by MS. • It is used by 3rd party tools • It is only 210 kB • It seems very simple to use • It does not seem to require installation • It’s free