This seems to be a simple question but there are many factors to be considered IMO:

1) How much better is the pay? 20% more? 50% more?100% more?
For me I jump only i at least got 20% more or if I am greddy 50%

2) Company wise and environment
Which company do you prefer? ur current one or the next one? u also have to consider the stability of the company. Like me I am in MNC now, if the next company that offers me more money is a chinaman company, I want it to be 80-100% more than what I earn now knowing full well the reputation of these companies.

3) Job scope
Are they the same job scope? Which do you u prefer and which one has higher chances of moving up?

2 weeks only ok lah...if u want to hop better hop now .. in the same think wisely compare the con and pro -> location, salary, benefit, working enviroment and opportunity

same situation here.
i got another interview although i had an offer on hand.

n im in my resigning notice period now.

Weight out the pros and cons if you leave your current job for new one. Make sure it is a good one because there's no point of leaving if there insignificant difference between those two jobs.

less than one year

my problem solved now
went for the interview n i dun like the job.

so i can stick 2 my offer.

u worked 2 weeks and u wanna job hop? i onli start for a week in tis new company & i'm gonna take my 2nd MC (which includes tomorrow, 19/06/06) of the week. so that i can go for 2nd interview and another IT job interview at the same day. so, go figure. 

if the prospect is good, go ahead. if ur current employee wanna fire u, so be it. if they dun, fine. read the letter of offer before u throw them the resign letter. for my case, i need to give 1 week notice for resignation even tho stil 1 week into the new job. if not, u gotta pay them back edi.

If there is a better pay and enviroment is ok to hop there. freshies always job hop in the first 2 years, but is not advisable to do so. If you found a place where u can stay and learn, try not to hop within a year. Yet it always depends on what enviroment you are working.

working life... argh~ i miss study.

it is depends on which company offer you better future and benefit.
In fact, you still have to consider which job you're more comfortable in...