Honestly, just start off with an 18 int, make sure you take Thunderwave if your WIS isn't completely pitiful, and *absolutely* take Flaming Sphere, and you'll be golden
(Especially if you have a special mini for flaming sphere, hehe)
If you want the full PHB-style orb wizard build, I'll throw a post together... it's not hard, just it doesn't completely guarantee a sleep-lock until epic tier.
If you want a fun build, go for a Battlemage! Pick Eladrin, Human, or Tiefling. For your implement, choose Staff of Defense. For your first feat, pick up Armor Proficiency (Leather). Second one is up to you.
For a stat spread, pre-racial try something like this, if you want to pick up hide armor later for another ac point: STR 13, CON 13, DEX 10, INT 16, WIS 14, CHA 10
Grab Thunderwave and w/e other at-will you'd like. Grab Burning Hands for your lv1 encounter (close power), and Flaming Sphere as the obvious daily choice. For your lv2 utility, take Shield. For your lv3 encounter, pick up Color Spray or Fire Shroud (also close powers).
Here's an in-depth analysis, if you're looking to build something on your own:
Stats: 18 int is a must, honestly; you roll more attack rolls due to all the area attacks you make. 20 might or might not be overkill, but it depends on your choices. If you want to pick up a shield, you'll need 13str. For hide armor, you need 13str/13con.
At-will powers: Thunderwave is just pure win... blast damage + push is lovely. Cloud of Daggers is awesome if your group does a lot of push/pull/slide stuff, but if not, pretty meh. Magic missile is always a classic, and is incredibly long range, but not terribly powerful for obvious reasons. Ray of Frost is nice for keeping big guys near the defender if you're ranged-heavy, but it's a bit more situational. Scorching Burst is fun for ranged burst at-will action.
Encounter lv1: Icy Terrain is nice for controlling an area and knocking stuff down, opening things up for your party. Chill Strike's daze is always a welcome feature.
Daily lv1:
Flaming Sphere. Period. No, I'm serious, it's amazing. Other options: Freezing Cloud will wipe out a nice, large area of minions, and deal decent damage. Acid Arrow = damage. Sleep only has 25% chance of even noticeably affecting a target for one round. For a daily? Blech. Sure, it's got broken applications, but you can just retrain for it later or keep it in your spellbook.
Utility lv2: Expeditious Retreat can give you a lot of room to maneuver when you'd otherwise be doomed. Shield comes up often enough where it'll
always get used in an encounter. Jump lets you grant someone else movement in combat, and enables jumping over obstacles easily. Feather Fall is a bit too situational for my tastes, but it depends on your DM.
Encounter lv3: Color Spray provides an excellent effect. Fire Shroud reliably targets almost any enemy, and deals fire damage. Icy Rays is nice for keeping enemies from leaving the defender or running around/away (skirmishers/artillery killer), Shock Sphere blows things up (but also targets allies unlike Fire Shroud)
Long-term concerns
In paragon tier, you need 15 Con for hide armor specialization (if you go that route). You need 15 Dex for arcane reach, an amazing feat. You need 13 Cha for Spell Focus, which is nice if you're using a few save ends effects (or are going for orb wizard).