Define "right away." Your pagerank will increase, but it will take a couple weeks for the search engines to connect your site to the high
PR sites (depending on how often those sites are crawled) and then you'll have to wait a few more days for Google to evaluate your pagerank and increase it.
Be careful when buying high
PR links. John Scott has a great program here, but some others can actually hurt your
PR if Google has them marked as spamming or permalink sites.