...for setting the table...
(pottery barn place setting - dinner and appetizer plates, bowls, mugs)
You're going to need the basics, and I suggest a minimum of 8 - 12 sets of each. Dinner plates, appetizer plates, bowls, forks, spoons, knives, drinking glasses, coffee mugs, wine glasses, rocks glasses, fabric napkins, and place mats and/or table cloths.
White and round are the way to go for the place settings. Patterned and colored plates take away from the meal, and it really is more appetizing to eat off a simple and clean white plate.
If you're looking for ways to add some style to your table, get some unique and colorful drinking glasses and napkins. I adore my Anthropologie hobnail glasses; We get so many compliments on them. They're just feminine enough, and - since they're clear - they mesh well with any place setting. If you love bright colors or patterns, put this toward your napkins (like these or these). They only take up a small portion of the table, so it's not overwhelming. And you can match them to the seasons/holidays.
beyond the basics: pick up some cappuccino cups, delicate cocktail coupes, high quality steak knives, or soup crocks. All of these are conversation starters and make dining/entertaining that much more enjoyable!
(sweet and saucy white pedestal bowl - perfect for sauces)
Dinner and cocktail parties are all about the presentation. Purchase platters of different sizes - a few long and skinny for appetizers, small and rectangular for side dishes, large for entrees, and square bowls for veggies and salads and such.
It's easiest to keep all the serving platters in the same color family. When you start to put out a few metal dishes, some glass stands, and a wood platter, your dinner spread looks disorganized. Stick with all white. It's usually the cheaper option anyways.
beyond the basics: add in some height with cake stands (like this or this or this). Cake stands are an area in which you can buy different materials (glass, porcelain, milk glass) and colors to add some fun to your table. Despite their name, cake stands are not only for dessert. Use them for dinner rolls, appetizers, or to raise a plate of veggies to another height.
A good kitchen doesn't require tons and tons of equipment. You'll need a medium sized aluminum pan, medium sized nonstick pan, large pasta pot, small sauce pan, casserole dish, edged sheet pan, plastic spoon, wooden spoon, tongs, collander, and cutting board. One area that costs a bit of money, but pays back in dividends is the knife set. At a minimum, you need a chef's knife and serated knife. Do yourself a favor - buy a high quality knife. If you clean it and sharpen it, the knife will love you forever.
(crate and barrel casserole dish with cork - for setting straight on the table)
Try and buy a good looking casserole dish, so that if you make your guests a lasagna (or another baked entree), you could set it directly on the table and not be embarassed.
beyond the basics: small prep bowls keep me organized and meat thermometers bring me sanity. Although their pricey, our All Clad pans were one of my favorite wedding gifts - good pans make tasty food!
Pick up a rectangular brownie pan (just get the kind with the lid for easy storage), sheet pan, spatula, measuring spoons, measuring cups, whisk, and oven mitts.
beyond the basics: a mini cupcake pan is great for baking little treats for dinner parties or birthday presents, a Silpat makes baking more dependable and simplifies cleaning, and a Kitchenaid mixer will make baking infinitely easier. If you plan on baking up a storm, pick up a cupcake holder or cake carrier for easy transportation.
...completely unnecessary but absolutely wonderful...
These items don't really fit in the categories above, but they bring me joy in the kitchen.
(making guinness ice cream with my ice cream attachment)
Ice Cream Maker Attachment: it's fairly small and easy to store (we keep ours in our freezer) and you simply connect it to your Kitchenaid mixer when you're ready to churn ice cream. And you can make completely unique flavors like Guinness ice cream.