win7中写的winforms应用程序在win xp上看起来不同.为什么？

我已经创建了一个示例来展示它在win 7和xp上的外观.
我可以做些什么来在两个系统上看到相同的外观？
问题不仅在于背景和字体颜色,还在于控件.在这里,我展示了数字版本的外观,但是对于表格布局我也有问题.

private void InitializeComponent()
    {
        this.numericUpDown1 = new System.Windows.Forms.NumericUpDown();
        this.groupBox1 = new System.Windows.Forms.GroupBox();
        ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).BeginInit();
        this.SuspendLayout();
        // 
        // numericUpDown1
        // 
        this.numericUpDown1.DecimalPlaces = 2;
        this.numericUpDown1.Increment = new decimal(new int[] {
        1,131072});
        this.numericUpDown1.Location = new System.Drawing.Point(21,26);
        this.numericUpDown1.Maximum = new decimal(new int[] {
        1,0});
        this.numericUpDown1.Name = "numericUpDown1";
        this.numericUpDown1.Size = new System.Drawing.Size(54,22);
        this.numericUpDown1.TabIndex = 0;
        // 
        // groupBox1
        // 
        this.groupBox1.Location = new System.Drawing.Point(21,82);
        this.groupBox1.Name = "groupBox1";
        this.groupBox1.Size = new System.Drawing.Size(226,99);
        this.groupBox1.TabIndex = 1;
        this.groupBox1.TabStop = false;
        this.groupBox1.Text = "groupBox1";
        // 
        // Form1
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(8F,16F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.BackColor = System.Drawing.SystemColors.ActiveCaption;
        this.ClientSize = new System.Drawing.Size(407,331);
        this.Controls.Add(this.groupBox1);
        this.Controls.Add(this.numericUpDown1);
        this.Name = "Form1";
        this.Text = "Form1";
        ((System.ComponentModel.ISupportInitialize)(this.numericUpDown1)).EndInit();
        this.ResumeLayout(false);

    }

我没有修改xp颜色主题.
我在win xp的两台不同的计算机上得到了相同的结果.