OK, in turn.
CADSTAR may work fine under Wine or crossover Office even under Linux. If you have a copy I'll happily try it on mine.
mounting memory cards works just fine unless you have some really weird card reader.
The Ubuntu disk can do all the shrinking/Dual boot/ etc for you even with NTFS. And yes, its now fully read/write safe from Linux.
AVG nope, Spyblaster - nope, no need for any of these things. If you want to be really friendly to your mates etc you can install and AV to scan so you don't accidentally forward an already infected email that you have received ( but obviously had no effect under Linux)
PDFs there are a number of PDF readers under Linux installed by default or you can run Adobe acrobat under Wine if you really must
Are you certain your printer driver isn't there by default? One of the differences is that Linux uses modules that can be dynamically loaded when you plug a printer etc in so you may find that its supported already without the need for 'drivers'. You may find them offered for download for the geeks that compile their own stuff from source code for everything.
For reference though Ubuntu uses the Debian .deb format for binary packages. but you are better using the Synaptic Package manager to install stuff as it will then automatically check and upgrade it when new stable versions are released.
CD writing - K3B is my personal tool of choice but there are others as well. 9.04 has Brasero as default. You may need to install the non free MP3 codecs if you want to burn Mp3s to Audio CD or to rip CDs. This is purely a licensing issue in that Linux won't install non free stuff by default and you have to do it yourself.
One thing of note is that under Linux you usually have a choice of tool very much like under Windows but without the need to install dodgy copies to see which you prefer. If you really want to you can usually do a lot of stuff very easily from Command line if you are happy with typing text.
e.g. I downloaded a load of pictures from my DSLR and wanted a 'smaller' copy for use on web pages. change to teh directory the files were in
convert -resize 800x600 *.jpg
wait 30 secs or so
done.
Happy to help if you have any more Q's either here or on MSN(details on my profile page) etc.