I converted the entire series for 3.0 and ran it. I also converted my favorite, Assault on the Fire Giant's Citadel for 3.5, and I've run it three or four times for friends and at conventions. The modules are awesome, and they translate very well (even better in my opinion) to 3rd edition. There is some really beautiful playtesting and design in those adventures. As has been mentioned, the giants in third edition are quite deadly (particularly in comparison). I typically run the third edition versions for between 10th - 15th levels. Tehre is some balancing that needs to be done both in terms of proximity as well as number of creatures, but not too bad.
My experiences with Fire Giants, running at around 14th level, is consistently fantastic. It is a great break/enter/destroy adventure that gets to showcase the many and varied strengths of a powerful high-level party. The Fire Giant King (who is an advanced/classed FG) is a killing machine, but can fairly easily be dealt with by a party focusing on some crowd and environmental control. The ultimate reveal of the drow in the end (the first significant appearance of the drow) with Eclavada unleashing some really evil/powerful cleric badness, following all that meatgrinding is a terrific twist.