The GX150 sff it's very buggy because it is to small and it's not worth it .
Buy the gx240 and put any geforce 4 or quadro 4, 128 bit bus, 64/128 mb.
Don't use nvidia Fx series or ATI/Amd.

Since your GX150 is the small form factor model, you'll be limited to low-profile/half-height AGP graphics cards, which severely narrows your choices. If you're not too picky, an nVidia Geforce4 MX440 would be a great choice for it. I used to have one in my Dell Dimension 4300S (which is like a consumer-oriented version of the GX240 small desktop) and it worked great for Windows 98 gaming.

For your GX240 tower, I'd go for an nVidia Geforce3/4 Ti series card (maybe a Ti4200 if you can find one at a decent price). My GX150 tower has a GF4 Ti4200 and it's pretty good as well.

I'd recommend nVidia Detonator 43.45 or 45.23 drivers for those cards.

I have a mx440 and works fine. Don't recall any issues using latest bios.

Hello,
I also found a GX150 with a black Dell monitor (for $15) in perfect condition, there wasn't even any dust in it!
I installed win98 on it and it works great.
I want to add a video card to it. For testing I tried a normal GeForce MX440 128/128 and a Radeon 9600 128/128. Both work great, but of course I can't close the box. 😁
Now I'm looking for a low profile AGP card.
I want to ask which is better 64mb/128bit or 128mb/64bit for games, because I only found one that is 128/128 (MSI FX5500, but I will have to use DVI to VGA)
I also found a low profile Geforce 6200 256mb/64bit.

What video card would you recommend I get?

The fastest low profile AGP card you can get for Windows 98 is Radeon 9600. There were some variants with 128-bit bus. I believe there were some low-profile 128-bit GeForce 440MX too, but obviously without any shader support. And if you really lucky, you could obtain a low-profile Radeon 8500/9100.

GeForce 6200 DDR2 variants also work, although compatibility is lower. Why DDR2? All low profile 6200 are gimped with 64-bit bus and DDR2 memory is clocked higher and overclocks better.

I wonder if 128MB is needed?
Which one of these should I get?

GeForce 2 Gainward MX400 TV-Out 64MB DDR 128bit
GeForce 4 Gainward MX 440 64MB DDR 128bit
GeForce MSI FX5500 128MB DDR 128bit
GeForce Gainward 6200A 256MB DDR 64bit
GeForce Gigabyte N6200RH 256MB GDDR2 64bit

And yet I found a low-profile GeForce 4 MX440SE 128MB/128bit. I can't wait for it to arrive and test it.

And the other thing I want to ask about the PIII 933mhz is there any point in getting a better video card?
I mean these, if they are better?
GeForce MSI FX5500 128MB DDR 128bit
GeForce Gigabyte N6200RH 256MB GDDR2 64bit

Shouldn't I get them too. They are all $10 each.

I cut the plank, bent it and it turned out perfect.