law enforcement + GP300 = a recipe for disaster.
He should of looked into an MTS2000 that has real public safety accessories available, better support, and wider programming solutions.
They aren't that bad, I know of one agency next door to us (Douglas County, GA SO) that uses GP300's and some GP350's. I'd put them up against a Pro series radio or some of the low end Japanese radios anyday. The big weak points are the RSM connectors, even with the reinforcements, they aren't sturdy. The battery terminals are also fragile. The radio itself is a rock solid unit with decent performance, a 16 channel will do MDC and QCII signaling.
Some GP350's could do narrowband, and had a much better RSM connector.
DCSO has been using their GP's since 1996, most have been phased out for HT1000's and Kenwood TK-2180's lately. They are still in use at the jail.
To the OP, don't even try using any DOS RSS in any modern version of Windows (2000, XP, Vista, Win7). CPU speed is only a factor with older RSS, most newer RSS run fine in a pure DOS environment on a modern machine, provided it has a real serial port (most newer computers do not, and USB to serial adapters will not function in DOS).
I just programmed a ton of GE M-PD and M-PA portables on a Pentium 4 2.6GHz desktop, 2GB of RAM. Booted to DOS 6.22 from a floppy and ran the GE software from a small 120MB FAT16 partition on the HDD. Worked just fine. GE M-PD CNV 2.0 was written in 1990 and M-PA programmer was ver 12 (c) 1994. Amazed that it worked. (it wouldn't read or write on my old IBM PS/2 model 58 486SLC-2 desktop running DOS 6.22)