Shalom,
Ubunutu has a very good track record for one of the widest hardware support profiles I've ever seen.
Your graphics card will need some support to work properly with gaming.
http://www.pctipsbox.com/nvidia-linux-display-driver-16907-now-available/Without nvidia drivers you are wasting your time trying to game with Linux because the video drivers are critical for game playing.
The link above is for the geforce 8800 card, which is what I have. I've not gotten around to doing the Linux install. My Vista box is a little unstable and I may have to wait for SP1 for the Hebrew language pack before I go forth.
Before using the April 2008 Ubuntu release which probably has a stronger kernel, which is a requirement for proper gaming, make sure that video drivers exist. If not, use the previous Ubuntu release which has a full set of Linux drivers.
The dual boot issue is really a matter of knowing Ubuntu uses a different file and format than the grub.conf file most Red Hat admins are used to.
I have a Ubuntu box at home but its recently become the second OS on a box used constantly by my children. My experience is limited to doing a google search and then cutting and pasting the proper commands into Ubuntu. I did manage to get surprisingly far with that approach.
My day job has me as an RHCE and HP-UX CSE.
As this is a Linux question, this is the perfect forum in which to post.
SEP
Steven E Protter
Owner of ISN Corporation
http://isnamerica.com
http://hpuxconsulting.com
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Twitter: http://twitter.com/hpuxlinux
Founder http://newdatacloud.com