Is the 8800gts Nvidia still good?

I am looking to upgrade from my 2004 gforce 6600 to something a bit more modern, i currently have a pentium 4 3.40ghz with 1gb of ram. Any tips? i am looking to spend 100 max on the graphics card.

I think before you do anything you should add some more RAM.  Chances are you are like me and still running XP.  If that is the case, I think you can "see" up to 4 gb of RAM.  I am playing DA:O with 3 gb.  I'm using a Pentium Duo E6600 (two 2.4GHz) which I got two years ago (currently priced around $140) with a XFX GeForce 250 GTS graphics card ($130) but any decent card is going to require more RAM and some may also need a meatier Power Unit.  I'm running a 550 watt one right now.  Compared to most PC gamers I know I am practically in the era of top hats and high button shoes, however for now it fits my needs.  I choose to upgrade a little at a time so it isn't so painful (to my wallet).  
 
Oh, and the GeForce 250 is basically a shrunk down 9800 with better cooling.  I traded up from a 8500 which wasn't cutting the mustard.  If my 8500 wasn't doing great, I'd be hesitant on anything less than the 9800 series for reasonable results. They are going to run about $120-$140, too.  Of course the same warning of what your motherboard, CPU, RAM requirements and Power needs still apply.

i would go for a 9800 at least if your hard up, but getting into the 200 range is better.

I didn't think the 8800gts was ever good?

by 100 do you mean 100 USD? A few weeks ago I bought a 9800 GT for £75 second hand, and hardware costs less in the US. I think you need to upgrade your processor and your ram also to make it worth it though. I'm running 2 GB of ram with vista and a 2.6 ghz AMD dual core processor as well as my 9800 GT 512 and I run Crysis on high at around 20-30 fps (other games runs much better naturally, I'm just using crysis as a yardstick. I can run UT3 and CoD 4 maxed out and get 60 FPS). If you get the 8800 you might be able to play some games from 4 years ago on full graphics with your other specs, but I guess if you just want to be able to play newer games then it might get you past the minimum requirements. Look around for the best deals on hardware.

i got the 512 gts and its pretty good. i would rate it 7/10 at this point since I do videocard based rendering now and 512mb is not enough and the card itself isnt that fast. HOWEVER, something like bad company 2 is really nice on it (but bc2 also uses the cpu a lot so you better have something equal to a phenom II 965 - my phenom 1 wasnt cuttin it). I'd call the gts 512 a budget card, but definetly not bad. 
 
**if you want to get technical, the 8800 gts 512 has a g92 chip so its pretty much a 9000 series card and it supports CUDA compatibility mode 1.1)

9 series is a repackaged 8 series.
 
I have 2 9800 GT SC cards in my rig and they still do wonders on my 24 inch monitor. 
 
A single one may still do a decent job on medium settings, though. Just make sure you get a 55nm version