Monster graphics

Now I know how many and what type of graphics I need, and I can start replacing my scratch graphics with finals. I downloaded a royalty free model and wrote a quick display program which shows the model and exports it to a bitmap. I then loaded these into Photoshop, tweaked them slightly, added shadows etc. I am going to have 16 frames of animation for each monster -
1 standing still
3 walking towards the player
3 walking left (flipped for walking right)
3 walking away
3 attacking
3 dying

I could, of course, have loaded the model straight into the game but there's a couple of reasons why I'm sticking to the flat 2d graphics. One is aesthetic, the game is a throwback to the old dungeon crawlers so I want it to have a semi-retro feel (even though it's in full 3d). The second reason is the target devices, the main goal is to be able to play this on a netbook which aren't the most powerful machines. If it gets ported to mobile devices there may be even less processing power.