Sharepoint can be a great tool, but the challenge is you are very dependant on your IT department to set it up in a way that meets your needs. There is a lot of logic built into a CRM system that will have to be relayed to your developers. Perhaps your company has used a pre-built Sharepoint based solution. If not, I would certainly make a case to your superiors that you cannot do the job to the best of your ability without a full featured CRM product.
CRM products have 100's of thousands of lines of code. While sharepoint is a nice technology, it's going to take a lot of work to get something that resembles a CRM system.
If you have the option, you might want to check out the free personal edition from Salesforce. Your bosses may not like the inability to get a peak into your data, but if they are using sharepoint I would bet that they aren't getting much useful data currently.
Most sales people see a CRM product as a hinderance, so it might be favorable to settle for a inferior solution, but the advantages a well built CRM tool have for a sales professional are tremendous!
Justyn Howard
Sharepoint
