One thing you should be aware of is that there are several companies that makes usb serial adapters, each with different chipsets and drivers. And each chipset/driver install differently. The most commonly used chipsets are:
FTDI
Prolific
WCH
Silicon Labs
Prolific is the cheapest but also the worst, the drivers/chipset are simply incompatible with many devices and operating systems, including 64-bit systems, (even Prolific themselves actually does provide a 64-bit driver), they are simply too cheap and unstable.
The best chipset/drivers are the FTDI. These are very solid and compatible with most devices and almost all operating systems both 32 and 64-bit. These usb usb to serial adapter are a bit more expensive but well worth the money.