If you have a hard drive formatted with NTFS and you compress all your files then is the following true? I try to open file "a" it would have to read 3mb of data. if it was uncompressed it would have to read 5mb of data. The hard drive has to read less data so it would in turn be faster to compress as long as u have a fast processor to uncompress the data on the fly. My laptop has a merom CPU so with dual core it shouldnt make a big impact on cpu to decompress but it would help the hard drive becaues it has to read less data. and also how much cpu would it use? if i compress it shouldnt make a big difference on battery life correct? or should i leave everything uncompressed for best performace?

There was a time when hard disk were relatively slow that your premise would have been valid. However, these days hard disks are so fast with built in buffers, read ahead and other tweaks that the time spent compressing and decompressing would be wasted even with older CPUs. It would make little difference to battery life as the biggest drain on the battery as far as the hard disk is concerned is spinning the disk which is spinning continuously regardless of whether any data is being read or written. Stuart

"or should i leave everything uncompressed for best performace?" Yes, I agree with Stuart. Also compression can be a headache when you run into problems.

I disagree. Use performance monitor and run a test to see if in fact your system will benefit from compressed data. I would venture to say that most people would find a very slight performance boost. This has a lot to do with the amount and type of data you use. Performance monitor and other test suites will prove your choice. I read it wrong and answer it wrong too. So get off my case you peanut.