<A HREF="http://www.anandtech.com/video/showdoc.html?i=1608&p=1" target="_new">This</A> is quite a comprehensive test. It contains the R8500, Ti4200, and the R8500LE 128MB. As you can see the Ti4200 beats everything by quite a bit. (except in games that are CPU bottlenecked, like Commanche4 and JK2) And that was the 128MB version which is clocked down from 250/250 of the 64MB version to 250/222, core/mem. If you get your brother's 1.4gig Athlon, you'd be rocking. The Ti4200 scales very well so you should probably get that if you can find it for ~$160 in a few weeks. I'd suggest putting off buying for at least a week or two to let the price for the Ti4200 settle down a bit. They usually start off the most expensive, then after a week they start to slide. If you get the Ti4200 you'll be able to play on 1280x1024x32. I think that that is the optimal resolution if you can run it smoothly.
Also some AA is good. One thing I have to admit that the Radeon cards do AA a lot faster than the NVidia ones do. They usually take a smaller performance hit with AA enabled. When getting OEM cards be sure that they are clocked at full speed. Many R8500LE OEM cards are clocked at 250/230 core/mem, which is lower than the 250/250 of the retail ones. If you want to be sure, then go for the retail one. A retail R8500LE 128MB and R8500 64MB cost about the same ~$160US. THis is a bit cheaper than the Ti4200 right now, but I'm sure both the prices will drop as more Ti4200s enter the pipeline.
As for the MX400, it will not be playable for many games at 1024x768x32. It will get around 30FPS which is not really playable. Also maybe you should get anothe 256MB of PC2100 RAM. They go for around $65. Other than that, you look fine. If you get your brother's 1.4gig Athlon, your card will scale quite nicely.
So in the end, look at the prices in a week or two and see which one is more worth it. Right now at these prices, I'd lean towards the Ti4200 128MB version since they have the extra 64MB of RAM which will help in future games and also in AA. THey will also cost a bit more, but if you'r not going to be upgrading again for a while, then what the heck. They'll be clocked at 250/222, but you can easily get it to the 64MB's 250/250, but more than likely you'll be able to get it close to the Ti4400's speed. <A HREF="http://www.hardocp.com/reviews/vidcards/nvidia/gf4ti4200/index.html" target="_new">Here's</A> a nice preview.
So I'm sure which ever one you get, you'll be able to run the games fine, but you have to think into the future and see when you'll be next upgrading. Also look at the price. Good Luck!
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