===Story=== Everybody's favorite aardvark swings into party mode on ''Arthur's Celebration''--to an Arthur-appropriate extent, anyway. How much boisterous merrymaking should we expect, after all, from the cartoon world's most buttoned-down 8-year-old? Mostly, this four-episode, 50-minute tip of the hat to fiestas features third-grade-caliber goof-ups. First up is "Arthur's Birthday," a bummer as it happens because it's also Muffy's big day, and she won't budge when it comes to changing her party date. It's up to Arthur, then, to work it out so their mutual pals won't have to party hop or pick and choose. In "Arthur's New Year's Eve," our hero's heart is set on staying up till midnight. Does the sky really glow green in a cosmic flash, as Francine would have him believe, or will everybody be wagering on a baby versus old-man wrestling match, the way Binky says? A down-in-the-dumps Grandma Thora is the intended guest of honor in "Grandma Thora Appreciation Day," but Arthur and D.W., in their party-planning fervor, forget her invitation, setting a new record for soiree screwups. The delightfully self-involved D.W. steals the show in the final episode, "D.W.'s Perfect Wish." Frightfully near her fifth birthday, she's determined to wish wisely--D.W.'s not one to "fribble" wishes away--for the year ahead. The party theme threads neatly through these clever-as-ever episodes, but the real fun of this tape is, as usual, the tightly drawn characters and their dear, distinctive perspectives on all manner of predicaments. ''-Tammy La Gorce''