OK, here's what I know...
Mactobe said:
C++ compiler and a simple IDE such as Bloodshed etc
Xcode 2 comes with Tiger and includes gcc4 plus associated IDE. I'm a Java-man myself so I can't comment on how well this works for C++ but it looks pretty good. Hell, the new Xcode 2 will, apparently, produce UML diagrams of you code, so that's a plus for me.
Mactobe said:
Compatibilty with a Speedtouch USB DSL modem.
Seems to vary by model from what I can tell. I have a USB/Ethernet SpeedTouch 530 that is Mac-compatible and certainly some of the USB-only models claim Mac compatability. That said I've some that aren't so definitely one to check on the SpeedTouch web site, I think.
Mactobe said:
Microsoft Office (very important, at least Excel and ideally Access).
MS provides Office 2004 for OS X which is, by and large, a great suite of applications and includes Word, Excel, PowerPoint and Entourage (sort of Outlook). I prefer Mac Office 2004 to PC Office 2003 (mostly due to the formatting palette) but the performance isn't great and it does lack Access. Additionally, Office 2004 seems to be more tailored to the personal/small office users rather than the enterprise, particularly when you look at the supplied templates. I guess MS reckons they have a strangle-hold on the corporate world and didn't think Office 2004 would be used there. Still, Offce 2004 includes most of the bells and whistles of Office 2003, including things like SmartTags.
As noted by others, there are alternatives to Access, such as FileMaker, which appears to be a reasonably priced bit of kit from which you could probably import your existing Access databases. However, I don't think FileMaker ships with a native Access driver so you might need a 3rd Party one. Best to check.
Mactobe said:
Does Oracle 8i run on the Mac?
I don't think so. Oracle, as far as I am aware, only just started to support the Mac by releasing 10g for OS X, so I don't think 8i is going to be available (although I could be wrong). However, while you can download the 10g version for free for development usage, it appears that it is only available for Mac OS X Server. I've not tried downloading it to see if it will run on plain vanilla OS X but the requirements page wasn't a good omen.
Depending on your database requirements, MySQL might be sufficient for you but if it has to be Oracle (or support stuff like stored procedures) then I think you'll have trouble.
Mactobe said:
Any decent flightsims? (I am studying for my PPL and can justify it)
No idea on this one. It's been many years since I've played a flight simulator (Fleet Defender on a 486 was the last one) so I can't say if any of these are decent, but try this
Flight Sim 2004 Roundup. Personally, I'm more into blowing **** up and started playing stuff like Tie Fighter rather than Falcon or MS Flight Simulator...