minecraft crash at start

When I click the play demo on minecraft, the program shuts down and shows that it has crashed and to try again. But every time I try again, it shows the same issue as before. . see attachments

my pc HP Pavilion s3407c
RAM 2.00 GB
Processor AMD Athlon Dual processor 4600+ 2.5 GHz
WINDOWS VISTA HOME PREMIUM SERVICE PACK 2

JAVA VERSION : VERSION 7 UPDATE 55