MacVector not only calculates the melting temperature (Tm) for any primers you design, but also displays the recommended annealing temperature (Ta) that you should use in PCR experiments using those primers. You can access the main MacVector interface for designing pairs of primers using Analyze | Primer Design (Primer3). From here you can ask MacVector to search for suitable primers using the popular Primer3 algorithm, or simply test a pair of existing primers for suitability. In either case, one of the output options is a Primer3 Spreadsheet tab.
Here the Tm of the Left and Right primers is displayed, along with the Tm of the product. The far right column also displays the recommended Ta for that primer pair. For more details on how this is calculated, please check out a recent blog post on the subject.