I just wanna share with you guys some of the things I used in maintaining my client pc on my internet cafe. Since I am operating 10 hours a day and 7 days a week day it is needed to perform maintenance at least once a month to prolong the life of the unit. So here it is:

1. Disc Defragmentation. Fragmentation occurs when the operating system breaks files into pieces of packets. Defragmentation allows you to organize the files inside your physical drives, it is the process of scanning the files and rejoining the split packets back into one.
2. Proper cleaning of unit. Basically when cleaning your pc's hardware make sure to unplug first the cord from the outlet and dry your hands. I usually clean the parts by using a paint brush and a pencil eraser, gently brush the the motherboard with the brush until all dirts remove. Use eraser in cleaning the TIP of any removable parts (Memory, VC, SC) inside the unit, make sure to do it gently.
3. Update your spy and adware program removal. I use Spybot search and Destroy, for me it is the best spy and adware removal program and it's FREE.

Good luck ^_^