Welcome to the world of Tablet Computing. Your question pertaining to whether you made a good purchase is not a simple one to answer. With inking capabilities one just can't go wrong, but it's deciding which tablet is right for you to sum up a good purchase or not.
If you'll be walking and inking with the M275 on your arm for the majority of the time your arms will be stronger than the strongest human alive...within a few weeks of course...5.7lbs becomes a heavy log after awhile.
On the other hand plans to use this TPC as a stationed tablet or just a laptop will make you very happy. Other than weight and not having the best resolution compared to Toshiba's M20X this tablet does it all. The sound can't be compared to any other tablet (2 nicely placed speakers give off great stereo sound). Such a standard makes for watching a DVD or listening to music a very pleasurable experience.
The 14.1" display will give you a large surface to write on and read from...w/o having to continuously scroll or strain your eyes. The large display led me to purchasing the M275 since drawing graphs on my notes takes up a lot of room and I hated not being able to surround my drawings with enough information w/o the need of adding more space on the page.
I've yet to have any performance problems with the M275, but its main function is for collecting the notes I take in lectures; therefore, the fact that it hasn't replaced my desktop leaves room for improvement.
The wireless card should pick up your network within the first few seconds of being on at your home...connected too if your network is not password protected. I do much of my school work outside w/o connection problems.
As far as the price you are going to pay it's a bargain. I purchased my last M275 with less memory and software than what is advertised on HSN.com but for just about the same amount, and that's because I'm a milatary vet so I don't pay taxes while purchasing from a military base.
Bottom line...you will not be disappointed unless you just have to have crystal clear resolution (not even Toshiba offers this) or are expecting to carry around a feather. Depending on how long you have to return your tablet, you may be able to read a review I'm planning to make between the M275 and M200 (once my ordered M200 ships). I'll probably take a few weeks so that I can make a fair assessment of the M200 (in store reviews and comparisons are hideous in explaining true details).
Once again welcome to the community, and I'm sure WNewquay will recommend some good links for you to read, they will get you up and running with inking technology.
Now go on and hit the refresh button to see if your M275 has shipped yet :D.