Not High Quality?
I just found out my Nvidia driver xP
That is a pretty old card. I have no idea if it would support whatever type of effect is used on the portal edges.
Also, have you updated your driver recently?
Yea, I did.
And when I did, I can't play HL2 anymore. (I still can play Deathmatch though.) (HL2 just crashes during loading screens)
Well, my way of figuring out the best buy is not to go for the cheapest, but to find the recommended requirements of the latest greatest graphic-intensive game, and buy based on that. 
(for me, usually 1 step above recommended, since I have the money).
The reasoning being. . .that the gaming market tends to build games based on "graphics engines", and if you can find out their sweet spot, you have a great likelyhood of lasting for quite a few years with the same card. If you go for less, you will find more and more games you will not be able to play as time goes on.. .
I believe we have met that requirement for the next couple of years with Crysis, whose specs are as follows:
Video Card: NVIDIA GeForce 6800 GT, ATI Radeon 9800 Pro (Radeon X800 Pro for Vista) or better
VRAM: 256MB of Graphics Memory
Recommended Requirements
Video Card: NVIDIA 7800 Series, ATI Radeon 1800 Series or better
VRAM: 512MB of Graphics Memory
(For the record, I have a GeoForce 8600 GTS, which does quite nicely)