How to build a PC?

The smart way, of course. Research, learn, design, plan, build, test. Then play Starcraft 2. HA!

Starting guiding question: How computers work? (Howstuffworks.com)

How to select the parts for your Frankenstein PC - from Tom's Hardware (excellent resources IMO):

• System Builder Marathon, Sept. 2010: Value Compared September 9, 2010 2:00 AM
  Three systems represent our builders' best performance and value hopes for budget, mainstream, and high-end users. 
• System Builder Marathon, Sept. 2010: $400 Gaming PC The third and final build in this quarter's
  System... September 8, 2010 2:00 AM
• System Builder Marathon, Sept. 2010: $1000 Enthusiast PC In this quarter's System Builder
  Marathon, we balance out... September 7, 2010 2:00 AM
• System Builder Marathon, Sept. 2010: $2000 Performance PC We bolstered our latest high-end
  build with a six-core... September6, 2010 2:00 AM 
• Power supply recommendations: http://www.silentpcreview.com/Recommended_PSUs
  (My summary: go for SeaSonic, Corsair, Enermax, Silverstone, Antec)

How to build a PC? (there are many books, magazines, web sites and YouTube videos about this, so get Googling and get some magazines!)
Recommended:

• How to Build a PC (AMD CPU in this video, Intel has a different CPU socket and heatsink) - Every Step Explained by Maximum PC
• How to build an Intel processor based PC (slightly different from the above)

And for the Singapore "Hardware Scene":

• http://www.hardwarezone.com.sg/

Look at their pricelist (you may have to become a member -it's free-) their shootouts, and their product guides (AKA reviews).

Tip: Never go cheap on motherboards or power supplies (PSUs), or you may regret it...

Good luck and happy building.