Personally, I like the Delphi IDE fine... You can customize it quite a lot, I hope you noticed? No, the versions released so far don't have a single "frame" (or "MDI") application-wide main window; but at least on Linux you could kind'a simulate that effect by giving it its own virtual desktop, couldn't you?
I haven't a clue about "RS232", except that 'serial' sounds like what is also known (from DOS) as "COM ports"... which, it seems, all belongs under the "[link|http://www.torry.net/modems.htm|Modems]" category at [link|http://www.torry.net/|Torry's]. (Which is to say, it sure seems possible; what Borland doesn't deliver in the package, others do.)
[Added on edit]: Silly me, quoting you the VCL (Win32) components... What you want is on the "[link|http://www.torry.net/comp_klx_comms.htm|Kylix Communications Components]" page, of course!
There's a lot less stuff there than on the Win32 page, but Lukas Gebauer's "SynaSer Serial Port Library" looks like it could be exactly what you need...? Anyway, it's "FWS" (Torry-speak for "FreeWare with Source"), so you can check it out at pretty much no risk or cost at all.