IMHO, I would say if you really have a stable resume in past, I mean showing experience of around 2 years or maybe 1.5 years in all the past 5 years then it is fine and you can take a switch if your present company HR doesnot take any action when you tell ask him about the salary.
My past job duration is something like this
1st company � 3 yrs 1month
2nd ,,- 1 yr
3rd - 10 months
4th- 1 yr 4 month
5th-present 3 month
[ June 02, 2005: Message edited by: Rahul Sen ]