You likely have several problems here; let's start with the USB cable. There's been a number of threads that have addressed this issue in the Uniden forum, and I'd encourage you to look at those first, to avoid rehashing the same topic. For example (anything in blue or underlined is a link - even though the topic discusses a 246, the answers are the same)
http://www.radioreference.com/forums/showthread.php?t=112754
Use the search tools to find all the posts regarding this topic. In general, getting the right drivers for Vista (sometimes these need to be installed- and run - as an administrator, not as an user), and being sure to assign an available COM port is going to get you going in the right direction. You didn't say what brand USB cable you got?
The best program for the 245 is
Scan Control In their accessories area they sell USB cables as well. In addition this program has a copy/paste utility that works with the RadioReference databases - something most every other 245 compatible program simply doesn't do.
Be more specific about what system(s) you want to program. The 245 is not capable of digital trunking, so if the areas you are interested in are using that format, it won't work. Look in our database, and supply the URLs of those system(s) so others can see what you are trying to do.
Finally we have a Trunking FAQ for the 245 in our wiki. It's linked here;
http://wiki.radioreference.com/index.php/The_BC245_Trunking_FAQ
73 Mike