krishnaraya,
I hold an Aussie PR from the past 4 years and I am still in U.S.A and have not gone to Australia since then except for a 2 day stay in Sydney enroute my India trip. I like Aussie land but I am still fighting in U.S.A for my Green card.
Aussie PR is tricky. It is not like U.S Green card. I don't know about U.K. But, I bet you that life is good in Australia. Even better than U.S. But the problem is jobs. You get jobs only if you have a PR unlike U.K or U.S. For canadian Immigration, one can apply on his own but not for Australian PR.
Australian Immigration authorities blindly believe their Registered Migration agents. This system is not found anywhere in the world. You can apply on your own but is very tedious as they will drop on you too many queries. So, what Mohammed said about Migration agents is correct as I too went through an Australian Migration Agent(Australian lady).
I disagree with Mohammed that a general IT professional will earn about 100K, the average pay rates for full time programmers/Analysts will be around 65K-70K. Australian companies are conservative and watch their spending very carefully. Also, getting a job is not easy in Australia. They don't spend much on technology. The office environment is too formal unlike U.S.A. For hiring you, they would have too many rounds of Interviews(Face to Face Interview is a must) unlike in U.S.A where you get hired off the phone and in rare cases, a F2F Interview.
One other con is that the cost of living and the pay you get are not proportional. Prices for example of Gasoline, Cars, Groceries are same as like U.S.A or U.K meaning. If a gallon of Gasoline in U.S.A is $3, then in Aussie, it will be converted into Aussie dollars and that is the price. A toyota camry in U.S.A is $20000 and in Aussie it is 30000 Aussie Dollars. But your salary will be still ~ $65k. Bottomline, is that you save very less.
Finally, I would say that is a better destination than Canada or NewZealand etc. I don't know about U.K. But U.S.A is altogether a different animal.
Wish you good luck!.
Chinnari.