I think the top six front-ends right now (in no particular order) are Mala, Mamewah, Maximus Arcade, GameEx, Hyperspin, and Atomic FE. My favorite is Hyperspin for its graphical glory. The Hyperspin team is in the midst or creating animated artwork for each individual game in Mame (clones excepted). They have themes for over 500 Mame games completed at the moment. The easiest setup I ever did was Maximus Arcade. I had it running in within 10 minutes of completing the download with a generated list and no issues. GameEx is reasonably easy, well supported, and flexible. After setting up GameEx, Maximus, Hyperspin, and Mala I tried downloading Mamewah and it was too difficult for me to justify finishing the setup process. GameEx, Maximus & Hyperspin are all free to try, but they do require registration fees to get the most out of them.
If you've been gone three years, then you may not know about Future Pinball. You should take a look at that (
www.futurepinball.com). It won't be running on your Pentium III. Daphne is still around and much easier to get working with the new Daphne Loader.
Act Labs is still around, but you will also want to check out the TopGun LCD. Both guns have their fans, but the three big advantages for the TopGun are: a) the technology allows machine gun fire emulation -- the Act Labs can only do single shot; 2) the TopGun will work with non-CRT screens; & 3) the TopGun is way cheaper. There are lots of review threads on these forums for both guns. The Topgun software drivers sucked when they first came out, but I hear those problems are mostly a thing of the past. I haven't got mine installed yet.
You can always check the what's new lists at mamedev.org to see what's been added, but three years is a lot of releases to go through. It's probably easiest to see what isn't emulated yet, and for that go here:
http://unmamed.mame.net/The latest thing starting with release 128 is the beginning of support for laserdisc games in MAME. Figure you need 13GB of hard drive space for each MAME laser disc game you want to support. So far only Cubequest, Firefox, M.A.C.H. 3, and Us vs. Them are supported, but there about 50 or so laserdisc games that could be emulated so buy a big hard drive.
With a 3 year hiatus, you've also missed the release of two different models of the ultimate all-in-one joystick -- Groovy Game Gear's GP-Wiz49 and 49 way joystick with optional rotary joystick modification kit and the Ultimarc Ultrastik 360. See
http://www.groovygamegear.com and
http://ultimarc.comIf you want a pretty front end, then you're going to want video snapshots of each of the games to play during game selection. For that go to emumovies.com. You can register and get FTP access and the DVD's of everything or you can hunt around for one of the torrents that Circo has released. Most of the front ends use the AVI format videos, but Hyperspin uses FLV's so download the format appropriate to your front end.