From memory, I think this is normal, at least in the days of early LOA's and such. They do not publish the computer choice until fairly late.
Past two years it's really just been do you get the optional kit of stuff. Monitor, printer, etc.
There are dozens of threads on the pro's and con's, so while waiting it might be worth scanning them.
Short version: Pretty much no cadet has ever come back and said they regreted buying or not buying the package.
You'll need a printer. The monitor is less clear. Many cadets like it. Others never use them and don't want the extra clutter on their desk.
You'll want a surge supressor & external hard drive. And a mouse of your choice.
I have inexpensive access to top tier computer & printer gear, so DS chose to save some money and do his own thing. Got a better printer and mouse. Sent his monitor home, chose not to keep it. He bought the USMA recommended external hard drive by itself when the computer was issued.
There is something to be said for having a standard config that the goldcoats will support, but the cadets we know who went with a non-standard printer have not had any problems. Nor are supplies an issue, they even sell 2-3 mfgs of printer cartridges in the cadet bookstore. (The printer mfg can vary from year to year)
So this is not something to worry about. The biggest computer issues you'll encounter will be when the laptops flake out and the goldcoats reimage it. Which seems to happen way more than it should! Computer slow? Reimage. Virus? Reimage!
So that external hard drive is probably the most critical device, as you'll lose your files if you don't back them up there. Flash drive and other removable media access is disabled, so it's your best backup.