The UBCD can be your savior when your PC behaves like a spoilt brat
System
There are numerous DOS-based (as is the case with all the utilities on UBCD) diagnostic and benchmark tools in this section that provide you information about the various components of the motherboard, CPU, memory, peripherals, etc.
AIDA16 is a system information utility that gives you information about the various components in the PC. There are six other such tools, some of which can also benchmark the system.
i think Hiren's Boot CD is not completely legal, so i dont think it will feature on this site. UBCD consists of completely freeware, but Hiren's has some illegal content
i always trust UBSD4WIN, when it comes to rescue and recovery of the systems. using it from past 4 years, earlier it was known as BartCD, if i am right. a really trustworthy and useful freeware. unless u dont mess deeply with compiler. just update the driverpacks, and anti viruses, and go on.
I have found Hiren's Boot CD to be more useful for my Windows system. I haven't tried anything on Linux but it is certainly recommended when your OS crashes and you want to back up important files in C Drive before formatting your OS partition.