i learnt that lesson when i got my first computer, it was a:
Celeron skt478 2.8GHz
256MB PC 333
onboard intelly gfx card
and sum other parts
It was made by HP...
When it came to the upgrading.... i was in the same boat as you!!
From then on, i always buidl my own.. its saves the pounds and hassle.
Cant you say it has a problem? (fiddles with pc) and complain? Then ask for a refund?