I also began programming using TP back around the late 80s and liked it so much I decided to make programming a profession. After going through school I ended up programming FORTRAN and SAS on mainframes and PV-WAVE and ARC/INFO on IBM RS/6000 UNIX systems. Once on the UNIX systems it was clear that "C" was the language to use. Everything was written in it. It was extremely portable.
I have also done a fair amount of Delphi programming on Windows. Delphi to TP is basically what Visual Basic is to QBASIC. It's an object oriented graphical development environment for Windows. I definitely prefer Delphi over VB. However, I have gotten so anti-M$ that I don't program in any of those Windows specific languages any more.
TP, Delphi, VB are all Windows specific languages. There are no UNIX versions (well, actually you can get Pascal compilers and there is GNU Pascal but Borland didn't create a version that I am aware of). You want to program in a portable cross-platform language you need to learn C, C++, and to a lesser extent Java. Also, Perl is a good cross platform scripting language (Actually, Perl can also be compiled into binary form).
Having said that, I do very little programming any more in compiled languages. I have become more fond of administration and networking over the last 8 years or so but still do a significant amount of scripting and web/database programming useing Shell scripts, Perl, PHP, PostgreSQL, MySQL, Sybase, etc... But I think any programmer (who's horizons run above M$) would tell you that you can not go wrong by learning C and/or C++ as a baseline.
[ July 30, 2002: Message edited by: VoidMain ]