Hallo Abhishek,

for simple tasks I would recommend you one of the VELLEMAN's scopes.
I use PCS500, two channel 50MHz digital storage scope with sample rate of up to 1GHz. It's a bit costly, but very very helpful... By the way, it's not a PC card, but comes in an own housing. This need not to be disadvantegous, because suppression of RFI is much easier, when moduls are separated and individually shielded.

Kai