Oracle Database Discussions

Hi,

I had installed Oracle 11g in windows 7, it is running good but problem is when i start or ON the computer it is taking about 3 minutes to get desktop screen and after that i could not open any applications (like MS word, Adobe reader,etc because it is hanging completely) for 10 minutes after getting desktop. This is really frustrating me every time i put on the computer. In frustration these are the questions firing in my mind....

Why this is Happening?
Is my system really working good?
Oh, this is may be because of oracle as i just installed the previous day?
Wow, Oracle is really working great, but why it is killing my computer as well as me?
Did Oracle support my computer or the configuration i have?
Should i go to the computer service center for tuning my computer performance?
Do i really want this heavier version of Oracle 11g rather than having older version of Oracle 10g Express edition?
and more...

So someone please tell me what will be the issue in it. Before i was using Oracle 10g XE, no issues i had with it. After that i formatted my system and installed the same OS and then Oracle 11g.
I don't have any other heavier application or any application that start at windows startup. I disabled all small startup programs that i have. Still no use.

These are the versions and configurations i have...

Oracle version:
Personal Oracle Database 11g Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for 32-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production

Operating System:
Windows 7 Ultimate
32-bit OS
1.8GHz Core 2 Duo
1GB RAM

This is the main question i want to ask...Is there any option to no auto startup the database along with the OS startup? So that i can start database manually when i want to work on Oracle.

Please Help!!!