BSOD; Possible RAM issue?

Hello, community.

Recently(4 days ago), I began receiving BSOD crashes while using my pc.

The BSOD would usually occur while either watching media or playing video games. But now, they seem to be coming randomly even when just browsing the internet.

I bought this pc from a friend and before I had internet, the PC would never have BSOD problems.

Ever since last week after the windows update, I began receiving BSOD crashes.

When the BSOD occurs, I receive this message: IRQL_NOT_LESS_OR_EQUAL_TO

I remember receiving that on my old Windows XP pc a few years back and never got rid of the problem.

A few hours ago, after I received the BSOD crash, my PC would try to reboot but become stuck and made a buzzing noise. I could hear the fan still on but my monitor screen became blank.

So I unplugged my PC and removed the case so I could clean the RAM. After a quick dusting, I reinserted the RAM back but in the other available slots and turned back on my PC. It seems to work as of now since I am on here typing. :P

So I was wondering if this BSOD issue may be a hardware RAM issue?

Questions:

1) How can I tell if my RAM sticks are faulty?

2) Is there more than one problem that can cause the IRQL_NOT_LESS_OR_EQUAL_TO BSOD error?

3) If the culprit is a faulty RAM stick, will replacing the RAM eliminate the problem?

Thanks!

EDIT: I received these messages after being able to reboot my pc. Does it mean anything?
Windows
Problem: Shut down unexpectedly
Files that help describe the problem:
061011-17721-01.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110611-0506.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110611-0506-01.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110609-1604.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110606-1407.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110602-2017.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.

Windows
Problem: Video hardware error
Files that help describe the problem:
WD-20110609-1330.dmp
sysdata.xml
WERInternalMetadata.xml
View a temporary copy of these files
Warning: If a virus or other security threat caused the problem, opening a copy of the files could harm your computer.