konnichiWA or konnichiHA

Do you know how to white "konnichiwa(good morning)"? In Japanese,
I thought we wrote "こんにちわ" as how we pronounce. If you google "こんにちわ(konnnichiwa)", 8,720,000 pages show up which means everybody is using "こんにちわ(konnnichiwa)" like I do.

One of my coworkers told me that is wrong. Actually, "こんにちは(konnnichiha)" is correct. As you may know, when "わ(wa)" is a focus particle, we white "は(ha)" even if we prononce "wa". What she said was that the greenting "konnnichiwa" is used to be "今日は、よいお天気ですね("konnnichiwa yoi otenki desune" : today is good weather), then it became shorter, so we need to write "こんにちは" because the "wa" is a focus particle.

Umm... It's like saying "hallo" as hello. I am a little embarrassed not to know until now... OK. I will stop writing "こんにちわ" then. ;-P