Rainstorm: Removing the .dll worked as far as speed goes for me too, but without it I get a different problem and that's that the screen goes black. (which gets removed by the player char. and moving the cursor around like an eraser, but it reappears within short again)
I tried different resolutions and compability modes to no avail, unfortunately it does lag, but I prefer that to not seing anything at all about once/30 secs. (and will try making a profile with everything to do with graphic acceleration turned off)
Just a warning that the removal of the file might not always work well...
Edit:
I have a Radeon 2600XT
Update:
I found a solution to my problem with timeslips patch:
http://timeslip.chorrol.com/sfall.html
Using his ddraw.dll I get the speed I got without the original but the blackening of the screen is gone.
I had to change graphics mode to 4 in ddraw.ini that came with it though, which causes a bit of pixelization of the movies, but I can easily live with that. :)

EvaUnit02: Hi Rainstorm, what setting in the ddraw.ini did you change to stop the screen from going black with the High Res patch + Sfall?
Was it ScaleFilter=4?

UK_John: I still have to say I prefer it in it's original 640x480, the way God intended a decade ago! :) I prefer close-up viewing of brains being splattered, etc! :)

kannabie: i would think exactly so, only if i had a CRT monitor. LCD monitors make everything that is below their stock res be too smudgy...

mechjman: Many thanks for the solution! (ddraw rename)
But I got another problem from this, I get pixels going missing because of this. Missing as in they are off coloured like a negative (shows up alot in the startup, but mostly disappears in running the game). I'm running vista with an Intel GMA900 graphics. Maybe the implementation of DX7/8 is crap on the Intel. Anyone got the same issues?

Cliftor: I think I got it, because I had the same problem as you.
First, out of curiosity, did you follow the nvidia control panel advice (making a profile for falloutw.exe) to turn everything off, and THEN do the ddraw.dll suggestion? I did, and I found that keeping the .dll advice but undoing the nvidia control panel advice fixed the "missing" pixels.
Let me know if that helped.
So many helpful people itt.

Max015: I have the missing pixels problem too. I'm running Vista with a RADEON XPRESS 200M Series card. 127 (318 total)mb dedicated memory.
Can you explain what you mean by the nvidia control panel advice please.
The game is too slow to be playable without deleting the dll but many graphics like the hp indicator are hard to read with this issue.
Any help, much appriciated!
Max

efin: Thanks for the DDraw fix! So much smoother now. :)
Also, I don't know if anyone else has had this problem, but with the hi-res pack I couldn't go anywhere in the radscorpion cave. I could move around the screen, but I couldn't scroll to go anywhere else other than the first bit you c an see. It appears to be wrong numbers put into an .ini file.
If you have this problem, go to the "f1_res" folder and open "map_edges_F1.ini" - in it you'll see the edges mapped out by number for each section of the game. Here is what I have for the Caves section:
NAME = CAVES
ELEVATION = 1
LEFT_EDGE = 1568
RIGHT_EDGE = 2540
TOP_EDGE = 1840
BOTTOM_EDGE = 1532
I'm not sure if these are accurate, but they worked for me. Have fun!

Cliftor: Don't minimize the game why you play? I'm sorry if that sounds silly of me, but the best advice I think is to not minimize fullscreen apps at all in general; it may be fine sometimes, but in my experience it causes unpredictable instability. I really just try to avoid it and I recommend that.

Regicide: If it were only that, I wouldn't have that much of a problem. However, when people instant message me and it happens (even though it doesn't minimize the game)... it can get really annoying. I don't want to have to sign out of Pidgin to play the game... :(