As for the Graphics Card, I'm guessing your using
PCI-E. You didn't mention a budget so
I'll give you a couple choices:

1. eVGA Geforce 7600GT - $189.00
($174.00 after $15.00 Mail-In Rebate)

THis one is pretty good, much better than
the 6800GT I have listed below this. This can
too play any game at max settings.

http://www.newegg.com/Product/Product.asp?Item=N82E16814130283

2. eVGA Geforce 7900GT - $319.00

http://www.newegg.com/Product/Product.asp?Item=N82E16814130281

This is very good. With this, you can play
all your most fun games at High Setting on everything
without any lag at all. I'm actually getting one
of these soon. Anyways.....

3. ASUS Geforce 6800GT - $219.99

http://www.newegg.com/Product/Product.asp?Item=N82E16814121192

This is a pretty good unit. This is a very
good video card, but will be outdated soon by the
7900GT and 7900GTX.

4. If you have alot of money, I mean alot, you
can take a look at this one below; this will last for a long time, very long. And if your system isn't
one of those $2000+ gaming systems, I wouldn't
suggest this, you won't get the performance out of
the card. Anyways, here it is:

ASUS Geforce 7900GTX - $589.99 Silly

http://www.newegg.com/Product/Product.asp?Item=N82E16814121002

Again, I wouldn't suggest buying this at all. The 7900GT is much better. And I know your current system
has ATI video, these are much better than ATI, trust me. Wink

As for a TV Tuner, here's what I suggest:

1.PLEXTOR PX-TV402U-NA -$187.00

http://www.newegg.com/Product/Product.asp?Item=N82E16814144505

This is a great unit, I saw is @ Circuitcity and it was awesome. The quality was great also. I would
suggest this over an internal device very much.
It's a bit pricy, but It will be money well spent.
Also, I don't know if you've heard of Newegg or not, but their prices are cheaper than lets say, Circuitcity or Best Buy.
Hope this helps and have a great day. :);):)

Sincerly,

CLuchetti